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ASTRONOMY FOR AMATEURS 




Paul Renaud. 



CONTEMPLATION 



r 



ASTRONOMY FOR 
AMATEURS 



BY 

CAMILLE FLAMMARION 

AUTHOR OF POPULAR ASTRONOMY 



AUTHORIZED TRANSLATION BY 

FRANCES A. WELBY 



ILLUSTRATED 




D. APPLETON AND COMPANY 
NEW YORK MCMIV 



Two nnn»«is !?*»r*»jvei1 

StP 23 1904 
Conyrfffht Entry 

CLASS OL XXo. No 

' COPY B 



T 



Copyright, 1904, by 
D. APPLETON AND COMPANY 



Puhlished October, 190U 






TO 

Madame C. R. CAVARE 

ORIGINAL MEMBER OF THE ASTRONOMICAL SOCIETY OF FRANCE 
CHATEAU DE MAUPERTHUIS 



Madame : I have dedicated none of my works, save Stella 
— offered to the liberal-minded, the free and generous friend 
of progress, and patron of the sciences, James Gordon Bennett, 
editor of the New York Herald. In this volume, Madame, I 
make another exception, and ask your permission to offer it to 
the first woman who consented to be enrolled in the list of mem- 
bers of the Astronomical Society of France, as foundress oi this 
splendid work, from the very beginning of our vast association 
(1887); and who also desired to take part in the permanent 
organization of the Observatory at Juvisy, a task of private 
enterprise, emancipated from administrative routine. An 
Astronomy for Women ^ can not be better placed than upon 
the table of a lady whose erudition is equal to her virtues, 
and who has consecrated her long career to the pursuit and 
service of the Beautiful, the Good, and the True. 

Camille Flammarion. 

Observatory of Juvisy, No'vemher^ ^QOJ- 

^ The French edition of this book is entitled Astronomy for Women.— ■ 
Translator. 



CONl^ENTS 



CHAPTER PAGE 

Introduction : . . . . . . i 

I. The Contemplation of the Heavens. . lo 

II. The Constellations 28 

III. The Stars, Suns of the Infinite. A Jour- 

ney through Space 56 

IV. Our Star the Sun . . . , . 88 
V. The Planets. A. :\Iercury, Venus, The 

Earth, Mars 113 

VI. The Planets. B. Jupiter. Saturn, Uranus, 

Xeptune 146 

VII. The Comets . . . . ^ . . .172 

VIII. The Earth 205 

IX. The IMoon 232 

X. The Eclipses ....... 259 

XI. On ^Iethods. How Celestial Distances 
ARE Determined, and How the Sun is 

Weighed 287 

XII. Life, Universal and Eternal . , .317 

Index 341 



LIST OF ILLUSTRATIONS 



Contemplation Frontispiece 

From a painting by Paul Renaud 

FIG. PAGE 

1. The great Book of the Heavens is open to all eyes . . 15 

2. The earth in space. June solstice, mid-day . . .20 

3. The Great Bear (or Dipper) and the Pole Star . . 34 

4. To find the Pole Star . . ^ 2>S 

5. To find Cassiopeia . 37 

6. To find Pegasus and Andromeda 37 

7. Perseus, the Pleiades, Capella 38 

8. To find Arcturus, the Herdsman, and the Northern 

Crown 40 

9. The Swan, Vega, the Eagle 41 

10. The Constellations of the Zodiac: summer and autumn; 

Capricorn, Archer, Scorpion, Balance, Virgin, Lion. 46 

11. The Constellations of the Zodiac: winter and spring; 

Crab, Twins, Bull, Ram, Fishes, Water-Carrier . 47 

12. Orion and his celestial companions . . . .48 

13. Winter Constellations .51 

14. Spring Constellations . . o . . . . 52 

15. Summer Constellations 53 

16. Autumn Constellations . ^ .... 54 

17. The double star Mizar 69 



ASTRONOMY FOR AMATEURS 



Triple star I in Cancer 
Quadruple star e of the Lyre 
Sextuple star B in the Nebula of Orion 
The Star-Cluster in Hercules 
The Star-Cluster in the Centaur . 
The Nebula in Andromeda . 
Nebula in the Greyhounds . 

The Pleiades 

Occultation of the Pleiades by the Moon 

Stellar dial of the double star v of the Virgin 

Comparative sizes of the Sun and Earth 

Direct photograph of the Sun 

Telescopic aspect of a Sun-Spot . 

Rose-colored solar flames 228,000 kilometers (141,500 

miles) in heigth, i.e.y 18 times the diameter of the 

Earth 

Orbits of the four Planets nearest to the Sun 

Orbits of the four Planets farthest from the Sun 

Mercury near quadrature . 

The Earth viewed from Mercury 

The Evening Star 

Successive phases of Venus . 

Venus at greatest brilliancy 

The Earth viewed from Venus . 

Diminution of the polar snows of Mars during the 

summer 136 

Telescopic aspect of the planet Mars (Feb., 1901) . 137 
Telescopic aspect of the planet Mars (Feb., 1901) . 138 



LIST OF ILLUSTRATIONS 



PAGE 
140 



Chart of Mars 

The Earth viewed from Mars 
Telescopic aspect of Jupiter 
Jupiter and his four principal satellites 
Saturn ...... 

Varying perspective of Saturn's Rings, as seen from 

the Earth 161 

The Great Comet of 1858 174 

What our Ancestors saw in a Comet . . . .177 

After Ambroise Pare (1858) 

Prodigies seen in the Heavens by our Forefathers . 178 

The orbit of a Periodic Comet 182 

The tails of Comets are opposed to the Sun . . 185 

A Meteor 191 

Shooting Stars of November 12, 1799 .... 196 

From a contemporary drawing 

Fire-Ball seen from the Observatory at Juvisy, August 

10, 1899 199 

Explosion of a Fire-Ball above Madrid, February 10, 

1896 ......... 200 

Raphael's Fire-Ball {The Madonna 0} Foligno) , . 202 

A Uranolith 203 

Motion of the Earth round the Sun . . . .222 

Inclination of the Earth 224 

The divisions of the globe. Longitudes and latitudes 226 

To find the long and short months .... 230 

The Full Moon slowly rises . . . . . 234 

The Moon viewed with the unaided eye . . . 236 

The Man's head in the Moon 237 



ASTRONOMY FOR AMATEURS 



FIG. 
67. 

68. 
69. 

70. 

71- 

72. 

73- 
74- 

75- 

76. 

77. 



79- 

80. 
81. 
82. 
83. 



Woman's head in the Moon 

The kiss in the Moon 

Photograph of the Moon 

The Moon's Phases . 

Map of the Moon 

The Lunar Apennines 

Flammarion's Lunar Ring 

Lunar landscape with the Earth in the sky 

Battle between the Medes and I>ydians arrested by an 

Eclipse of the Sun 

Eclipse of the Moon at Laos (February 27, 1877) 

The path of the Eclipse of May 28, 1900 

Total eclipse of the Sun, May 28, 1900, as observed 

from Elche (Spain) . 
The Eclipse of May 28, 1900, as photographed^ by 

King Alfonso XIII, at Madrid . 
Measurement of Angles .... 
Division of the Circumference into 360 degrees 
Measurement of the distance of the Moon , 
Measurement of the distance of the Sun 
Small apparent ellipses described by the stars as a 

result of the annual displacement of the Earth 



238 

239 
240 
241 
247 
251 
253 
254 

266 
269 

273 

281 

285 
289 
291 
292 
297 

306 



INTRODUCTION 



The Science of Astronomy is sublime and beautiful. 
Noble; elevating, consoling, divine, it gives us v^ings, 
and bears us through Infinitude. In these ethereal 
regions all is pure, luminous, and splendid. Dreams 
of the Ideal, even of the Inaccessible, w^eave their subtle 
spells upon us. The imagination soars aloft, and aspires 
to the sources of Eternal Beauty. 

What greater delight can be conceived, on a fine 
spring evening, at the hour when the crescent moon is 
shining in the West amid the last glimmer of twilight, 
than the contemplation of that grand and silent spec- 
tacle of the stars stepping forth in sequence in the vast 
Heavens ? All sounds of life die out upon the earth, 
the last notes of the sleepy birds have sunk away, the 
Angelus of the church hard by has rung the close of 
day. But if life is arrested around us, we may seek it 
in the Heavens. These incandescing orbs are so many 
points of interrogation suspended above our heads in 
the inaccessible depths of space. . . . Gradually they mul- 
tiply. There is Venus, the white star of the shepherd. 
There Mars, the little celestial world so near our own. 

I 



ASTRONOMY FOR AMATEURS 

There the giant Jupiter. The seven stars of the Great 
Bear seem to point out the pole, while they slowly 
revolve around it. . . . What is this nebulous light that 
blanches the darkness of the heavens, and traverses 
the constellations like a celestial path ? It is the Galaxy, 
the Milky Way, composed of millions on millions of 
suns! . . . The darkness is profound, the abyss immense. 
. . . See! Yonder a shooting star glides silently across 
the sky, and disappears! . . . 

Who can remain insensible to this magic spectacle 
of the starry Heavens ? Where is the mind that is not 
attracted to these enigmas ? The intelligence of the 
amateur, the feminine, no less than the more material 
and prosaic masculine mind, is well adapted to the con- 
sideration of astronomical problems. Women, indeed, 
are naturally predisposed to these contemplative studies. 
And the part they are called to play in the education 
of our children is so vast, and so important, that the 
elements of Astronomy might well be taught by the 
young mother herself to the budding minds that are 
curious about every issue — whose first impressions 
are so keen and so enduring. 

Throughout the ages women have occupied them- 
selves successfully with Astronomy, not merely in its 
contemplative and descriptive, but also in its mathe- 
matical aspects. Of such, the most illustrious was the 

2 



INTRODUCTION 

beautiful and learned Hypatia of Alexandria, born 
in the year 375 of our era, public lecturer on geometry, 
algebra, and astronomy, and author of three works 
of great importance. Then, in that age of ignorance 
and fanaticism, she fell a victim to human stupidity 
and malice, was dragged from her chariot while cross- 
ing the Cathedral Square, in March, 415, stripped of 
her garments, stoned to death, and burned as a dis- 
honored witch! 

Among the women inspired with a passion for the 
Heavens may be cited St. Catherine of Alexandria, ad- 
mired for her learning, her beauty and her virtue. She 
was martyred in the reign of Maximinus Daza, about 
the year 312, and has given her name to one of the lunar 
rings. 

Another celebrated female mathematician was 
Madame Hortense Lepaute, born in 1723, who col- 
laborated with Clairaut in the immense calculations 
by which he predicted the return of Halley's Comet. 
*' Madame Lepaute,'' wrote Lalande, *'gave us such 
immense assistance that, without her, we should never 
have ventured to undertake this enormous labor, in which 
it was necessary to calculate for every degree, and for 
a hundred and fifty years, the distances and forces of the 
planets acting by their attraction on the comet. Dur- 
ing more than six months, we calculated from morning 

2 3 



ASTRONOMY FOR AMATEURS 

to night, sometimes even at table, and as the result of 
this forced labor I contracted an illness that has changed 
my constitution for life; but it was important to pub- 
lish the result before the arrival of the comet." 

This extract will suffice for the appreciation of the 
scientific ardor of Madame Lepaute. We are indebted 
to her for some considerable works. Her husband 
was clock-maker to the King. ''To her intellectual 
talents," says one of her biographers, ''were joined all 
the qualities of the heart. She was charming to a de- 
gree, with an elegant figure, a dainty foot, and such 
a beautiful hand that Voiriot, the King's painter, who 
had made a portrait of her, asked permission to copy it, 
in order to preserve a model of the best in Nature." And 
then we are told that learned women can not be good- 
looking! . . . 

The Marquise du Chatelet was no less renowned. 
She was predestined to her career, if the following anec- 
dote be credible. Gabrielle-Emilie de Breteuil, born 
in 1706 (who, in 1725, was to marry the Marquis du 
Chatelet, becoming, in 1733, the most celebrated 
friend of Voltaire), was four or five years old when she 
was given an old compass, dressed up as a doll, for a 
plaything. After examining this object for some time, 
the child began angrily and impatiently to strip off the 
silly draperies the toy was wrapped in, and after turning 

4 



INTRODUCTION 

it over several times in her little hands, she divined its 
uses, and traced a circle with it on a sheet of paper. To 
her, among other things, w^e ov^e a precious, and indeed 
the only French, translation of Newton's great work on 
universal gravitation, the famous Principia, and she was, 
with Voltaire, an eloquent propagator of the theory of 
attraction, rejected at that time by the Academie des 
Sciences. 

Numbers of other women astronomers might be 
cited, all showing how accessible this highly abstract 
science is to the feminine intellect. President des 
Brosses, in his charming Voyage en Italie, tells of the 
visit he paid in Milan to the young Italian, Marie 
Agnesi, who delivered harangues in Latin, and was 
acquainted with seven languages, and for whom mathe- 
matics held no secrets. She was devoted to algebra and 
geometry, which, she said, ''are the only provinces of 
thought wherein peace reigns." Madame de Charriere 
expressed herself in an aphorism of the same order: ''An 
hour or two of mathematics sets my mind at liberty, 
and puts me in good spirits: I feel that I can eat and 
sleep better when I have seen obvious and indisputable 
truths. This consoles me for the obscurities of religion 
and metaphysics, or rather makes me forget them; I 
am thankful there is something positive in this world/* 
And did not Madame de Blocqueville, last surviving 

5 



ASTRONOMY FOR AMATEURS 

daughter of Marshal Davout, who died in 1892, ex- 
claim in her turn: *' Astronomy, science of sciences! 
by which I am attracted, and terrified, and which I adore ! 
By it my soul is detached from the things of this world, 
for it draws me to those unknown spheres that evoked 
from Newton the triumphant cry: 'Cceli enarrant glo- 
riam DeiF 

Nor must we omit Miss Caroline Herschel, sister of 
the greatest observer of the Heavens, the grandest dis- 
coverer of the stars, that has ever lived. Astronomy 
gave her a long career; she discovered no less than 
seven comets herself, and her patient labors preserved 
her to the age of ninety-eight. — And Mrs. Somerville, 
to whom we owe the English translation of Laplace's 
Mecanique celeste, of whom Humboldt said, ''In 
pure mathematics, Mrs. Somerville is absolutely su- 
perior." Like Caroline Herschel, she was almost a 
centenarian, appearing always much younger than her 
years: she died at Naples, in 1872, at the age of ninety- 
two. — So, too, the Russian Sophie Kovalevsky, de- 
scendant of Mathias Corvinus, King of Hungary, who, 
an accomplished mathematician at sixteen, married 
at eighteen, in order to follow the curriculum at the 
University (then forbidden to unmarried women); ar- 
ranging with her young husband to live as brother and 
sister until their studies should be completed. In 1888 

6 



INTRODUCTION 

the Prix Bordin of the Institut was conferred on her. 
— And Maria Mitchell of the United States, for 
whom LeVerrier gave a fete at the Observatory of Paris, 
and who was exceptionally authorized by Pope Pius IX 
to visit the Observatory of the Roman College, at that 
time an ecclesiastical establishment, closed to women. 
— And Madame Scarpellini, the Roman astronomer, 
renowned for her works on shooting stars, whom 
the author had the honor of visiting, in company with 
Father Secchi, Director of the Observatory mentioned 
above. 

At the present time. Astronomy is proud to reckon 
among its most famous workers Miss Agnes Clerke, 
the learned Irishwoman, to whom we owe, inter alia, 
an excellent History of Astronomy in the Nineteenth 
Century; — Mrs. Isaac Roberts, who, under the familiar 
name of Miss Klumpke, sat on the Council of the Astro- 
nomical Society of France, and is D. Sc. of the Faculty of 
Paris and head of the Bureau for measuring star pho- 
tographs at the Observatory of Paris (an American who 
became English by her marriage with the astronomer 
Roberts, but is not forgotten in France); — Mrs. Flem- 
ing, one of the astronomers of the Observatory at Har- 
vard College, U. S. A., to whom we owe the discovery 
of a great number of variable stars by the examination 
of photographic records, and by spectral photography; — 

7 



ASTRONOMY FOR AMATEURS 

Lady Huggins, who In England is the learned collabora- 
tor of her illustrious husband; — and many others. 

The following chapters, which aim at summing up 
the essentials of Astronomy in twelve lessons for ama- 
teurs, will not make astronomers or mathematicians of 
my readers — much less prigs or pedants. They are 
designed to show the constitution of the Universe, in its 
grandeur and its beauty, so that, inhabiting this world, 
we may know where we are living, may realize our po- 
sition in the Cosmos, appreciate Creation as it is, and 
enjoy it to better advantage. This sun by which we 
live, this succession of months and years, of days and 
nights, the apparent motions of the heavens, these starry 
skies, the divine rays of the moon, the whole totality of 
things, constitutes in some sort the tissue of our existence, 
and it is indeed extraordinary that the inhabitants of our 
planet should almost all have lived till now without 
knowing where they are, without suspecting the mar- 
vels of the Universe. 

For the rest, my little book is dedicated to a woman, 
muse and goddess — the charming enchantress Urania, 
fit companion of Venus, ranking even above her in the 
choir of celestial beauties, as purer and more noble, 
dominating with her clear glance the irnmensities of 

3 



INTRODUCTION 

the universe. Urania, be it noted, is feminine, and 
never w^ould the poetry of the ancients have imagined 
a mascuhne symbol to personify the pageant of the 
heavens. Not Uranus, nor Saturn, nor Jupiter can 
compare with the ideal beauty of Urania. 

Moreover, I have before me tw^o delightful books, 
in breviary binding, dated the one from the year 1686, 
the other from a century later, 1786. The first w^as 
v^ritten by Fontenelle for a Marquise, and is entitled 
Entretiens sur la Pluralite des Mondes. In this, banter 
is pleasantly married v^ith science, the author declaring 
that he only demands from his fair readers the amount 
of application they v^ould concede to a novel. The 
second is written by Lalande, and is called Astronomic 
des Danies. In addressing myself to both sexes, I am 
in honorable company with these two sponsors and 
esteem myself the better for it. 



CHAPTER I 

THE CONTEMPLATION OF THE HEAVENS 

The crimson disk of the Sun has plunged beneath 
the Ocean. The sea has decked itself with the burning 
colors of the orb, reflected from the Heavens in a mirror 
of turquoise and emerald. The rolling waves are gold 
and silver, and break noisily on a shore already darkened 
by the disappearance of the celestial luminary. 

We gaze regretfully after the star of day, that poured 
its cheerful rays anon so generously over many who 
were intoxicated with gaiety and happiness. We dream, 
contemplating the magnificent spectacle, and in dream- 
ing forget the moments that are rapidly flying by. Yet 
the darkness gradually increases, and twilight gives way 
to night. 

The most indiff'erent spectator of the setting Sun 
as it descends beneath the waves at the far horizon, 
could hardly be unmoved by the pageant of Nature 
at such an impressive moment. 

The light of the Crescent Moon, like some fairy boat 
suspended in the sky, is bright enough to cast chan- 
ging and dancing sparkles of silver upon the ocean. The 

lO 



THE CONTEMPLATION OF THE HEAVENS 

Evening Star declines slowly in its turn toward the west- 
ern horizon. Our gaze is held by a shining world that 
dominates the whole of the occidental heavens. This 
is the " Shepherd's Star," Venus of rays translucent. 

Little by little, one by one, the more brilliant stars 
shine out. Here are the white Vega of the Lyre, the 
burning Arcturus, the seven stars of the Great Bear, 
a whole sidereal population catching fire, like innu- 
merable eyes that open on the Infinite. It is a new life 
that is revealed to our imagination, inviting us to soar 
into these mysterious regions. 

O Night, diapered with fires innumerable! hast 
thou not written in flaming letters on these Constella- 
tions the syllables of the great enigma of Eternity .? 
The contemplation of thee is a wonder and a charm. 
How rapidly canst thou efface the regrets we suffered 
on the departure of our beloved Sun ! What wealth, 
what beauty hast thou not reserved for our enraptured 
souls ! Where is the man that can remain blind to 
such a pageant and deaf to its language! 

To whatever quarter of the Heavens we look, the 
splendors of the night are revealed to our astonished 
gaze. These celestial eyes seem in their turn to gaze 
at, and to question us. Thus indeed have they ques- 
tioned every thinking soul, so long as Humanity has 
existed on our Earth. Homer saw and sung these 

1 1 



ASTRONOMY FOR AMATEURS 

self-same stars. They shone upon the slow succession 
of civilizations that have disappeared, from Egypt of 
the period of the Pyramids, Greece at the time of the 
Trojan War, Rome and Carthage, Constantine and 
Charlemagne, down to the Twentieth Century. The 
generations are buried with the dust of their ancient 
temples. The Stars are still there, symbols of Eternity. 

The silence of the vast and starry Heavens may 
terrify us; its immensity may seem to overwhelm us. 
But our inquiring thought flies curiously on the wings 
of dream, toward the remotest regions of the visible. 
It rests on one star and another, like the butterfly on 
the flower. It seeks what will best respond to its as- 
pirations: and thus a kind of communication is estab- 
lished, and, as it were, protected by all Nature in these 
silent appeals. Our sense of solitude has disappeared. 
We feel that, if only as infinitesimal atoms, we form part 
of that immense universe, and this dumb language of 
the starry night is more eloquent than any speech. Each 
star becomes a friend, a discreet confidant, often indeed 
a precious counsellor, for all the thoughts it suggests 
to us are pure and holy. 

Is any poem finer than the book written in let- 
ters of fire upon the tablets of the firmament ? Noth- 
ing could be more ideal. And yet, the poetic senti- 
ment that the beauty of Heaven awakens in our soul 

12 



THE CONTEMPLATION OF THE HEAVENS 

ought not to veil its reality from us. That is no less 
marvelous than the mystery by which v^e v^ere en- 
chanted. 

And here we may ask ourselves how many there are, 
even among thinking human beings, who ever raise 
their eyes to the starry heavens ? How many men and 
women are sincerely, and with unfeigned curiosity, 
interested in these shining specks, and inaccessible 
luminaries, and really desirous of a better acquaint- 
ance with them ? 

Seek, talk, ask in the intercourse of daily life. You, 
who read these pages, who already love the Heavens, 
and comprehend them, who desire to account for our 
existence in this world, who seek to know what the 
Earth is, and what Heaven — you shall witness that the 
number of those inquiring after truth is so limited that 
no one dares to speak of it, so disgraceful is it to the 
so-called intelligence of our race. And yet! the great 
Book of the Heavens is open to all eyes. What pleas- 
ures await us in the study of the Universe! Nothing 
could speak more eloquently to our heart and intellect! 

Astronomy is the science par excellence. It is the 
most beautiful and most ancient of all, inasmuch as it 
dates back to the indeterminate times of highest an- 
tiquity. Its mission is not only to make us acquainted 
with the innumerable orbs by which our nights are 

13 



ASTRONOMY FOR AMATEURS 

illuminated, but it is, moreover, thanks to it that we 
know where and what we are. Without it we should 
live as the blind, in eternal ignorance of the very con- 
ditions of our terrestrial existence. Without it we 
should still be penetrated with the naive error that re- 
duced the entire Universe to our minute globule, ma- 
king our Humanity the goal of the Creation, and should 
have no exact notion of the immense reality. 

To-day, thanks to the intellectual labor of so many 
centuries, thanks also to the immortal genius of the 
men of science who have devoted their lives to search- 
ing after Truth — men such as Copernicus, Galileo, 
Kepler, Newton — the veil of ignorance has been rent, and 
glimpses of the marvels of creation are perceptible in 
their splendid truth to the dazzled eye of the thinker. 

The study of Astronomy is not, as many suppose^ 
the sacrifice of oneself in a cerebral torture that oblit- 
erates all the beauty, the fascination, and the grandeur 
of the pageant of Nature. Figures, and naught but fig- 
ures, would not be entertaining, even to those most 
desirous of instruction. Let the reader take courage! 
We do not propose that he shall decipher the hiero- 
glyphics of algebra and geometry. Perish the thought! 
For the rest, figures are but the scaffolding, the method, 
and do not exist in Nature. 

We simply beg of you to open your eyes, to see where 

14 




Fig. I. — The great Book of the Heavens is open to all eyes. 



ASTRONOMY FOR AMATEURS 

you are, so that you may not stray from the path of 
truth, which is also the path of happiness. Once you 
have entered upon it, no persuasion will be needed to 
make you persevere. And you will have the profound 
satisfaction of knowing that you are thinking correctly, 
and that it is infinitely better to be educated than to be 
ignorant. The reality is far beyond all dreams, beyond 
the most fantastic imagination. The most fairy-like 
transformations of our theaters, the most resplendent 
pageants of our military reviews, the most sumptuous 
marvels on which the human race can pride itself — 
all that we admire, all that we envy on the Earth — • 
is as nothing compared with the unheard-of wonders 
scattered through Infinitude. There are so many that 
one does not know how to see them. The fascinated 
eye would fain grasp all at once. 

If you will yield yourselves to the pleasure of ga- 
zing upon the sparkling fires of Space, you will never 
regret the moments passed all too rapidly in the con- 
templation of the Heavens. 

Diamonds, turquoises, rubies, emeralds, all the 
precious stones with which women love to deck them- 
selves, are to be found in greater perfection, more 
beautiful, and more splendid, set in the immensity of 
Heaven ! In the telescopic field, we may watch the 
progress of armies of majestic and powerful suns, from 

l6 



THE CONTEMPLATION OF THE HEAVENS 

whose attacks there is naught to fear. And these vaga- 
bond comets and shooting stars and stellar nebulae, 
do they not make up a prodigious panorama ? What 
are our romances in comparison with the History of 
Nature ? Soaring toward the Infinite, we purify our 
souls from all the baseness of this world, we strive to 
become better and more intelligent. 

But in the first place, you ask, what are the Heavens ? 
This vault oppresses us. We can not venture to in- 
vestigate it. 

Heaven, we reply, is no vault, it is a limitless im- 
mensity, inconceivable, unfathomable, that surrounds 
us on all sides, and in the midst of which our globe is 
floating. The Heavens are all that exists, all 
that we see, and all that we do not see: the Earth on 
which we are, that bears us onward in her rapid 
flight; the Moon that accompanies us, and sheds her 
soft beams upon our silent nights; the good Sun to which 
we owe our existence ; the Stars, suns of Infinitude ; 
in a word — the whole of Creation. 

Yes, our Earth is an orb of the Heavens: the sky is 
her domain, and our Sun, shining above our heads, 
and fertilizing our seasons, is as much a star as the 
pretty sparkling points that scintillate up there, in the 
far distance, and embellish the calm of our nights 

17 



ASTRONOMY FOR AMATEURS 

with their briUiancy. All are in the Heavens, you as 
well as I, for the Earth, in her course through Space, 
bears us with herself into the depths of Infinitude. 

In the Heavens there is neither ''above" nor ''be- 
low." These words do not exist in celestial speech, 
because their significance is relative to the surface of 
this planet only. In reality, for the inhabitants of the 
Earth, ''low" is the inside, the center of the globe, 
and "high" is what is above our heads, all round the 
Earth. The Heavens are what surround us on all 
sides, to Infinity. 

The Earth is, like her fellows. Mercury, Venus, 
Mars, Jupiter, Saturn, Uranus, Neptune, one of the 
planets of the great solar family. 

The Sun, her father, protects her, and directs all her 
actions. She, as the grateful daughter, obeys him 
blindly. All float in perfect harmony over the celestial 
ocean. 

But, you may say, on what does the Earth rest in 
her ethereal navigation ? 

On nothing. The Earth turns round the colossal 
Sun, a little globe of relatively light weight, isolated 
on all sides in Space, like a soap-bubble blown by 
some careless child. 

Above, below, on all sides, millions of similar globes 
are grouped into families, and form other systems of 

i8 



THE CONTEMPLATION OF THE HEAVENS 

worlds revolving round the numerous and distant stars 
that people Infinitude; suns more or less analogous to 
that by w^hich w^e are illuminated, and generally speak- 
ing of larger bulk, although our Sun is a million times 
larger than our planet. 

Among the ancients, before the isolation of our * 
globe in Space and the motions that incessantly alter 
its position were recognized, the Earth was supposed 
to be the immobile lower half of the Universe. The 
sky was regarded as the upper half. The ancients 
supplied our world with fantastic supports that pene- 
trated to the Infernal Regions. They could not admit 
the notion of the Earth's isolation, because they had a 
false idea of its weight. To-day, however, we know 
positively that the Earth is based on nothing. The 
innumerable journeys accomplished round it in all 
directions give definite proof of this. It is attached to 
nothing. As we said before, there is neither ''above" 
nor ''below" in the Universe. What we call "below" 
is the center of the Earth. For the rest the Earth 
turns upon its own axis in twenty-four hours. Night 
IS only a partial phenomenon, due to the rotary motion 
of the planet, a motion that could not exist under con- 
ditions other than that of the absolute isolation of our 
globe in space. 

Since the Sun can only illuminate one side of our 
3 19 



ASTRONOMY FOR AMATEURS 

globe at one moment, that is to say one hemisphere, 
it follows that Night is nothing but the state of the 
part that is not illuminated. As the Earth revolves 
upon itself, all the parts successively exposed to the 



Fig. 2. — The earth in space. June solstice, midday. 

Sun are in the day, w^hile the parts situated opposite 
to the Sun, in the cone of shadow produced by the Earth 
itself, are in night. But whether it be noon or mid- 
night, the stars always occupy the same position in 

20 



THE CONTEMPLATION OF THE HEAVENS 

the Heavens, even when, dazzled by the ardent Hght 
of the orb of day, v^e can no longer see them; and 
when we are plunged into the darkness of the night, 
the god Phoebus still continues to pour his beneficent 
rays upon the countries turned toward him. 

The sequence of day and night is a phenomenon 
belonging, properly speaking, to the Earth, in which 
the rest of the Universe does not participate. The 
same occurs for every world that is illuminated by a 
sun, and endowed with a rotary movement. In abso- 
lute space, there is no succession of nights and days. 

Upheld in space by forces that will be explained at 
a later point, our planet glides in the open heavens 
round our Sun. 

Imagine a magnificent aerostat, lightly and rapidly 
cleaving space. Surround it with eight little balloons 
of different sizes, the smallest like those sold on the 
streets for children to play with, the larger, such as 
are distributed for a bonus in large stores. Imagine 
this group sailing through the air, and you have the 
system of our worlds in miniature. 

Still, this is only an image, a comparison. The 
balloons are held up by the atmosphere, in which they 
float at equilibrium. The Earth is sustained by nothing 
material. What maintains her in equilibrium is the 
ethereal void; an immaterial force; gravitation. The 

21 



ASTRONOMY FOR AMATEURS 

Sun attracts her, and if she did not revolve, she would 
drop into him; but rotating round him, at a speed of 
107,000 kilometers * (about 66,000 miles) per hour, 
she produces a centrifugal force, like that of a stone in 
a sling, that is precisely equivalent, and of contrary 
sign, to its gravitation toward the central orb, and 
these two equilibrated forces keep her at the same 
medium distance. 

This solar and planetary group does not exist solitary 
in the immense void that extends indefinitely around 
us. As we said above, each star that we admire in the 
depths of the sky, and to which we lift up our eyes and 
thoughts during the charmed hours of the night, is 
another sun burning with its own light, the chief of a 
more or less numerous family, such as are multiplied 
through all space to infinity. Notwithstanding the 
immense distances between the sun-stars. Space is so 
vast, and the number of these so great, that by an 
effect of perspective due solely to the distance, appear- 
ances would lead us to believe that the stars were 
touching. And under certain telescopic aspects, and 
in some of the astral photographs, they really do appear 
to be contiguous. 

The Universe is infinite. Space is limitless. If 

* I kilometer =r 0.6214 mile; 100 kilometers may be taken as 62 miles. 
I kilogram is about 2.2 lb.; 5 kilograms =11 lb. — Translator. 

22 



THE CONTEMPLATION OF THE HEAVENS 

our love for the Heavens should incite in us the impulse, 
and provide us with the means of undertaking a journey 
directed to the ends of Heaven as its goal, we should 
be astonished, on arriving at the confines of the Milky 
Way, to see the grandiose and phenomenal spectacle 
of a new Universe unfold before our dazzled eyes; and 
if in our mad career we crossed this new archipelago 
of worlds to seek the barriers of Heaven beyond them, 
we should still find universe eternally succeeding to 
universe before us. Millions of suns roll on in th*e 
immensities of Space. Everywhere, on all sides. Cre- 
ation renews itself in an infinite variety. 

According to all the probabilities, universal life is 
distributed there as well as here, and has sown the 
germ of intelligence upon those distant worlds that 
we divine in the vicinity of the innumerable suns that 
plow the ether, for everything upon the Earth tends 
to show that Life is the goal of Nature. Burning 
foci, inextinguishable sources of warmth and light, 
these various, multi-colored suns shed their rays 
upon the worlds that belong to them and which they 
fertilize. 

Our globe is no exception in the Universe. As we 
have seen, it is one of the celestial orbs, nourished, 
warmed, lighted, quickened by the Sun, which in its 
turn again is but a star, 

23 



ASTRONOMY FOR AMATEURS 

Innumerable Worlds! We dream of them. Who 
can say that their unknown inhabitants do not think 
of us in their turn, and that Space may not be traversed 
by waves of thought, as it is by the vibrations of light 
and universal gravitation ? May not an immense 
solidarity, hardly guessed at by our imperfect senses, 
exist between the Celestial Humanities, our Earth being 
only a modest planet. 

Let us meditate on this Infinity! Let us lose no 
opportunity of employing the best of our hours, those 
of the silence and peace of the bewitching nights, in 
contemplating, admiring, spelling out the words of 
the Great Book of the Heavens. Let our freed souls 
fly swift and rapt toward those marvelous countries 
where indescribable joys are prepared for us, and let 
us do homage to the first and most splendid of the 
sciences, to Astronomy, which diflPuses the light of 
Truth within us. 

To poetical souls, the contemplation of the Heavens 
carries thought away to higher regions than it attains 
in any other meditation. Who does not remember the 
beautiful lines of Victor Hugo in the Orientales .? Who 
has not heard or read them ^ The poem is called 
" Ecstasy," and it is a fitting title. The words are 
sometimes set to music, and the melody seems to com- 
plete their pure beauty: 

24 



THE CONTEMPLATION OF THE HEAVENS 

J'etais seul pres des flots par une nuit d'etoiles. 
Pas un nuage aux cieux, sur les mers pas de voiles ; 
Mes ycux plongeaient plus loin que le monde reel, 
Et les bois et les monts et toute la nature 
Semblaient interroger, dans un confus murmure, 
Les flots des mers, les feux du del. 

Et les etoiles d'or, legions infinies, 

A voix haute, a voix basse, avec mille harmonies 

Disaient, en inclinant leurs couronnes de feu ; 

Et les flots bleus, que rien ne gouverne et n'arrete, 

Disaient en recourbant Pecume de leur crete : 

C'est le Seigneur, le Seigneur Dieu ! 

Note : Free Translation 
I was alone on the waves, on a starry night. 
Not a cloud in the sky, not a sail in sight. 
My eyes pierced beyond the natural world 
And the woods, and the hills, and the voice of Nature 
Seemed to question in a confused murmur. 

The waves of the Sea, and Heaven's fires. 

And the golden stars in infinite legion. 
Sang loudly, and softly, in glad recognition. 
Inclining their crowns of fire ; . . . 
And the waves that naught can check nor arrest 
Sang, bowing the foam of their haughty crest 
Behold the Lord God — Jehovah ! 

25 



ASTRONOMY FOR AMATEURS 

The immortal poet of France was an astronomen 
The author more than once had the honor of conversing 
with him on the problems of the starry sky — and re- 
flected that astronomers might well be poets. 

It is indeed difficult to resist a sense of profound 
emotion before the abysses of infinite Space, when we 
behold the innumerable multitude of worlds suspended 
above our heads. We feel in this solitary contempla- 
tion of the Heavens that there is more in the Universe 
than tangible and visible matter: that there are forces, 
laws, destinies. Our ants' brains may know them- 
selves microscopic, and yet recognize that there is some- 
thing greater than the Earth, the Heavens; — more 
absolute than the Visible, the Invisible; — beyond the 
more or less vulgar affairs of life, the sense of the True, 
the Good, the Beautiful. We feel that an immense 
mystery broods over Nature, — over Being, over created 
things. And it is here again that Astronomy surpasses 
all the other sciences, that it becomes our sovereign 
teacher, that it is the pharos of modern philosophy. 

O Night, mysterious, sublime, and infinite! with- 
drawing from our eyes the veil spread above us by the 
light of day, giving back transparency to the Heavens, 
showing us the prodigious reality, the shining casket 
of the celestial diamonds, the innumerable stars that 
succeed each other interminably in immeasurable space! 

26 



THE CONTEMPLATION OF THE HEAVENS 

Without Night we should know nothing. Without it 
our eyes would never have divined the sidereal popula- 
tion, our intellects would never have pierced the harmony 
of the Heavens, and we should have remained the blind, 
deaf parasites of a world isolated from the rest of the 
universe. O Sacred Night! If on the one hand it 
rests upon the heights of Truth beyond the day's illu- 
sions, on the other its invisible urns pour down a silent 
and tranquil peace, a penetrating calm, upon our souls 
that weary of Life's fever. It makes us forget the 
struggles, perfidies, intrigues, the miseries of the hours 
of toil and noisy activity, all the conventionalities of 
civilization. Its domain is that of rest and dreams. 
We love it for its peace and calm tranquillity. We love 
it because it is true. We love it because it places us in 
communication with the other worlds, because it gives 
us the presage of Life, Universal and Eternal, because 
it brings us Hope, because it proclaims us citizens of 
Heaven. 



27 



CHAPTER II 
THE CONSTELLATIONS 

In Chapter I we saw the Earth hanging in space, Hke 
a globe isolated on all sides, and surrounded at vast 
distances by a multitude of stars. 

These fiery orbs are suns like that which illuminates 
ourselves. They shine by their own light. We know 
this for a fact, because they are so far off that they 
could neither be illuminated by the Sun, nor, still more, 
reflect his rays back upon us: and because, on the other 
hand, we have been able to measure and analyze their 
light. Many of these distant suns are simple and 
isolated; others are double, triple, or multiple; others 
appear to be the centers of systems analogous to that 
which gravitates round our own Sun, and of which we 
form part. But these celestial tribes are situated at 
such remote distances from us that it is impossible to 
distinguish all the individuals of each particular family. 
The most delicate observations have only revealed a 
few of them. We must content ourselves here with 
admiring the principals, — the sun-stars, — prodigious 

28 



THE CONSTELLATIONS 

globes, flaming torches, scattered profusely through the 
firmament. 

How, then, is one to distinguish them ? How can 
they be readily found and named ? There are so many 
of them! 

Do not fear; it is quite a simple matter. In study- 
ing the surface of the Earth we make use of geographical 
maps on which the continents and seas of which it 
consists are drawn with the utmost care. Each country 
of our planet is subdivided into states, each of which 
has its proper name. We shall pursue the same plan 
in regard to the Heavens, and it will be all the easier 
since the Great Book of the Firmament is constantly 
open to our gaze. Our globe, moreover, actually re- 
volves upon itself so that we read the whole in due 
sequence. Given a clear atmosphere, and a little 
stimulus to the will from our love of truth and science, 
and the geography of the Heavens, or ''uranography," 
will soon be as familiar to us as the geography of our 
terrestrial atom. 

On a beautiful summer's night, when we look to- 
ward the starry sky, we are at first aware only of a number 
of shining specks. The stars seem to be scattered 
almost accidentally through Space; they are so numer- 
ous and so close to one another that it would appear 
rash to attempt to name them separately. Yet some 

29 



ASTRONOMY FOR AMATEURS 

of the brighter ones particularly attract and excite our 
attention. After a little observation we notice a certain 
regularity in the arrangement of these distant suns, 
and take pleasure in drawing imaginary figures round 
the celestial groups. 

That is what the ancients did from a practical point 
of view. In order to guide themselves across the track- 
less ocean, the earliest Phenician navigators noted cer- 
tain fixed bearings in the sky, by which they mapped 
out their routes. In this way they discovered the posi- 
tion of the immovable Pole, and acquired empire over 
the sea. The Chaldean pastors, too, the nomad people 
of the East, invoked the Heavens to assist in their 
migrations. They grouped the more brilliant of the 
stars into Constellations with simple outlines, and gave 
to each of these celestial provinces a name derived from 
mythology, history, or from the natural kingdoms. 
It is impossible to determine the exact epoch of this 
primitive celestial geography. The Centaur Chiron, 
Jason's tutor, was reputed the first to divide the Heavens 
upon the sphere of the Argonauts. But this origin is 
a little mythical! In the Bible we have the Prophet 
Job, who names Orion, the Pleiades, and the Hyades, 
3,300 years ago. The Babylonian Tables, and the 
hieroglyphs of Egypt, witness to an astronomy that 
had made considerable advance even in those re- 

30 



THE CONSTELLATIONS 

mote epochs. Our actual constellations, which are 
doubtless of Babylonian origin, appear to have been 
arranged in their present form by the learned philoso- 
pher Eudoxus of Cnidus, about the year 360 B.C. 
Aratus sang of them in a didactic poem toward 270. 
Hipparchus of Rhodes was the first to note the astro- 
nomical positions with any precision, one hundred and 
thirty years before our era. He classified the stars in 
order of magnitude, according to their apparent bright- 
ness ; and his catalogue, preserved in the Almagest of 
Ptolemy, contains 1,122 stars distributed into forty- 
eight Constellations. 

The figures of the constellations, taken almost en- 
tirely from fable, are visible only to the eyes of the 
imagination, and where the ancients placed such and 
such a person or animal, we may see, with a little good- 
will, anything we choose to fancy. There is nothing 
real about these figures. And yet it is indispensable 
to be able to recognize the constellations in order to 
find our way among the innumerable army of the stars, 
and we shall commence this study with the description 
of the most popular and best known of them all, the 
one that circles every night through our Northern 
Heavens. Needless to name it; it is familiar to every 
one. You have already exclaimed — the Great Bear! 

This vast and splendid association of suns, which is 

31 



ASTRONOMY FOR AMATEURS 

also known as the Chariot of David, the Plow or 
Charles's Wain, and the Dipper, is one of the finest 
constellations in the Heavens, and one of the oldest^ — 
seeing that the Chinese hailed it as the divinity of the 
North, over three thousand years ago. 

If any of my readers should happen to forget its 
position in the sky^ the following is a very simple ex- 
pedient for finding it. Turn to the North — that is, 
opposite to the point where the sun is to be found at 
midday. Whatever the season of the year, day of the 
month, or hour of the night, you will always see, high 
up in the firmament, seven magnificent stars, arranged 
in a quadrilateral, followed by a tail, or handle, of three 
stars. This magnificent constellation never sinks be- 
low our horizon. Night and day it watches above us, 
turning in twenty-four hours round a very famous star 
that we shall shortly become acquainted with. In the 
figure of the Great Bear, the four stars of the quadri- 
lateral are found in the body, and the three at the ex- 
tremity make the tail. As David's Chariot, the four 
stars represent the wheels, and the three others the 
horses. 

Sometimes our ancestors called them the Seven 
Oxen, the ''oxen of the celestial pastures," from 
which the word septentrion (septern trtones, seven oxen 
of labor) is derived. Some see a Plowshare; others 

32 



THE CONSTELLATIONS 

more familiarly call this figure the Dipper. As it 
rotates round the pole, its outline varies with the differ- 
ent positions. 

It is not easy to guess why this constellation should 
have been called the Bear. Yet the name has had a 
certain influence. From the Greek word arctos (bear) 
has come arctic, and for its antithesis, antarctic. From 
the Latin word trio (ox of labor) has come septen- 
trion, the seven oxen. Etymology is not always logical. 
Is not the word 'Venerate" derived from Venus ? 

In order to distinguish one star from another, the 
convention of denoting them by the letters of the Greek 
Alphabet has been adopted, for it would be impossible 
to give a name to each, so considerable is their number.* 

a and /3 denote the front wheels of the Chariot 
generally known as the " pointers;" 7 and S the hind 
wheels; e, f, 7; the three horses. All these stars are 
of the second order of magnitude (the specific mean- 
ing of this expression will be explained in the next 
chapter), except the last (8) of the quadrilateral, which 
is of the third order. 

*It is useful to know the letters of the Greek Alphabet. They are easily 
learned, as follows : 



a Alpha 


f] Eta 




V Nu 


T Tau 


/3 Beta 


e Theta 




i xi 


V Upsilon 


y Gamma 


i Iota 




Omicron 


(/) Phi 


S Delta 


K Kappa 




Tr Pi 


xChi 


€ Epsilon 


A Lambda 




p Rho 


i|/ Psi 


C Zeta 


IX Mu 


33 


(T or s Sigma 


CD Omega 



ASTRONOMY FOR AMATEURS 

Figure 3 gives the outline of this pnmitive constella- 
tion. In revolving in twenty-four hours round the Pole, 
w^hich is situated at the prolongation of a line draw^n 
from ^ to a, it occupies every conceivable position, — 
as if this page v^ere turned in all directions. But 
the relative arrangement of the seven stars remains 
unaltered. In contemplating these seven stars it must 




Fig. 3. — The Great Bear (or Dipper), and the Pole-Star. 

never be forgotten that each is a dazzling sun, a center 
of force and life. One of them is especially remarkable: 
^, knov^n as Mizar to the Arabs. Those vs^ho have good 
sight will distinguish near it a minute star, Alcor, or 
the Cavalier, also called Saidak by the Arabs — that is, 
the Test, because it can be used as a test of vision. But 
further, if you have a small telescope at your disposal, 
direct it upon the fine star Mizar: you will be astonished 

34 



THE CONSTELLATIONS 

at discovering two of the finest diamonds you could wish 
to see, with which no brilHant is comparable. There 
are several double stars; these we shall become ac- 
quainted with later on. 

Meantime, we must not forget our celestial geography. 
The Great Bear will help us to find all the adjacent con- 
stellations. 

If a straight line is drawn (Fig. 4) from /? through a, 
which forms the extremity of the square, and is pro- 
longed by a quantity equal to the distance of a from 
the tip of the handle, we come on a star of second 
magnitude, which ^^^ 

marks the extremity ^ \^ 
of a figure perfectly ^ 4^ ^^^^-^ 

comparable with the f ^^ >^^ ^ 

Great Bear, but small- \ \ ^ 3^// | 

er, less brilliant, and Z^^-^" ^^ 

pointing in the con- p^^^ ^_r^^ ^^^ ^^^ Pole-Star 
trary direction. This 

is the Little Bear, composed, like its big brother, of 
seven stars; the one situated at the end of the line by 
which we have found it is the Pole-Star. 

Immovable in the region of the North Pole, the 
Pole-Star has captivated all eyes by its position in the 
firmament. It is the providence of mariners who have 
gone astray on the ocean, for it points them to the 

4 35 



Q/- 



ASTRONOMY FOR AMATEURS 

North, while it is the pivot of the immense rotation 
accompHshed round it by all the stars in twenty-four 
hours. Hence it is a very important factor, and we 
must hasten to find it, and render it due homage. It 
should be added that its special immobility, in the 
prolongation of the Earth's axis, is merely an effect 
caused by the diurnal movements of our planet. Our 
readers are of course aware that it is the earth that 
turns and not the sky. But evidence of this will be 
given later on. In looking at the Pole-Star, the South 
is behind one, the East to the right, and the West to 
the left. 

Between the Great and the Little Bear, we can 
distinguish a winding procession of smaller stars. 
These constitute the Dragon, 

We will continue our journey by way of Cassiopeia, 
a fine constellation placed on the opposite side of the 
Pole-Star in relation to the Great Bear, and shaped 
somewhat like the open limbs of the letter W. It is 
also called the Chair. And, in fact, when the figure 
is represented with the line a /3 below, the line x 7 forms 
the seat, and 7 8 e its back. 

If a straight line is drawn from S of the Great Bear, 
and prolonged beyond the Pole-Star in a quantity equal 
to the distance which separates these two stars, it is 
easy to find this constellation (Fig. 5). This group, 

36 



THE CONSTELLATIONS 



like the preceding, never sets, and is always visible, 
opposite to the Great Bear. It revolves in twenty- 






7*—* 



/?* 



-*-^. 



,c 



k! ^ 






Pole •^-"■"' 
'"]"•■'-■' Pole sYar" 






Fig, c. — To find Cassiopeia. 



four hours round the Pole-Star, and is to be seen, now 
above, now below, now to the right, now to the left. 

If in the next place, starting from the stars a and S 
in the Great Bear, we draw two lines which join at 











'Square 


of Per/asus 


<% 









..-4--- 


* 




- "i 

:?t .---'■' 


-^■/^ 


A 

/ 


; 

/ 

-^- 






---' Pole Star 


TUv 


—< 

y 


X 

















Fig. 6. — To find Pegasus and Andromeda. 

Polaris and are prolonged beyond Cassiopeia, we 
arrive at the Square of Pegasus (Fig. 6), a vast con- 

37 



ASTRONOMY FOR AMATEURS 

stellation that terminates on one side in a prolongation 
formed of three stars. 

These three last stars belong to Andromeda, and 
themselves abut on Perseus. The last star in the 
Square of Pegasus is also the first in Andromeda. 

7 of Andromeda is a magnificent double orb, to 
which we shall return in the next chapter, /. ^., the 
telescope resolves it into two marvelous suns, one of 
which is topaz-yellow, and the other emerald-green. 
Three stars, indeed, are visible with more powerful 
instruments. 

Above yS and near a small star, is visible a faint, 
whitish, luminous trail: this is the oblong nebula of 

^ Andromeda, the first mentioned in 

■ The Goat"'-'. ^^ %'' ^^^ history 01 astronomy, and one 

of the most beautiful in the Heav- 

\^ i ^ ens, perceptible to the unaided eye 

/ g Algol » r r / 

-^^ ^ on very clear nights. 

/- The stars « ^ and 7 of Per- 

'i^<J>leiades ' 

sens form a concave bow which 
Fig. 7. — Perseus, the will serve in a new orientation. 
Pleiades, Capella. j^ j^ j^ prolonged in the direction 
of S, we find a very brilliant star of the first magnitude. 
This is Capella, the Goat, in the constellation of the 
Charioteer (Fig. 7). 

If coming back to S in Perseus, a line is drawn 

38 



THE CONSTELLATIONS 

toward the South, we reach the Pleiades, a gorgeous 
cluster of stars, scintillating like the finest dust of dia- 
monds, on the shoulder of the Bull, to which we shall 
come shortly, in studying the Constellations of the 
Zodiac. 

Not far off is a very curious star, (^ of Perseus, or 
Algol, which forms a little triangle with two others 
smaller than itself. This star is peculiar in that, in- 
stead of shining with a fixed light, it varies in intensity^ 
and is sometimes pale, sometimes brilliant. It belongs 
to the category of variable stars which we shall study 
later on. All the observations made on it for more than 
two hundred years go to prove that a dark star revolves 
round this sun, almost in the plane of our line of sight, 
producing as it passes in front of it a partial eclipse 
that reduces it from the second to the fourth magni- 
tude, every other two days, twenty hours, and forty- 
nine minutes. 

And now, let us return to the Great Bear, which 
aided us so beneficently to start for these distant shores, 
and whence we shall set out afresh in search of other 
constellations. 

If we produce the curved line of the tail, or handle, 
we encounter a magnificent golden-yellow star, a splen- 
did sun of dazzling brilliancy: let us make our bow to 
Arcturus, a of the Herdsman, which is at the extremity 

39 



ASTRONOMY FOR AMATEURS 

of this pentagonal constellation. The principal stars 
of this asterism are of the third magnitude, with the 
exception of a, which is of the first. Alongside of 
the Herdsman is a circle consisting of five stars of 
the third and fourth magnitude, save the third, a, or the 
Pearl, which is of the second magnitude. This is the 
Corona Borealis. It is very easily recognized (Fig. 8). 
A line drawn from the Pole-Star to Arcturus 



L Xorthe^ni 
^ ik Crown 



>7 ,.^'^'""r'?-~ 



-^- 



•5 e 
4 






cc^ Arcturus 

Fig. 8. — To find Arcturus, the Herdsman, and the Northern 
Crown. 

forms the base of an equilateral triangle, the apex of 
which, situated opposite the Great Bear, is occupied 
by Vega, or a of the Lyre, a splendid diamond of ideal 
purity scintillating through the ether. This magnificent 
star, of first magnitude, is, with Arcturus, the most lumi- 
nous in our Heavens. It burns with a white light, in the 
proximity of the Milky Way, not far from a constella- 
tion that is very easily recognized by the arrangement 
of its principal stars in the form of a cross. It is named 
Cygnus, the Bird, or the Swan (Fig. 9), and is 

40 



THE CONSTELLATIONS 

easy to find by the Square of Pegasus, and the Milky 
Way. This figure, the brilhancy of whose constituents 
(of the third and fourth magnitudes) contrasts strongly 
with the pallor of the Milky Way, includes at its ex- 
tremity at the foot of the Cross, a superb double star, 
/S or Albirio : a of Cygnus is also called Deneb. 
The first star of which the distance was calculated is 
in this constellation. This little orb of fifth magnitude, 



74.. 



i^ Square of Pegasus 



■% 



^,-- ^ \t<ja 



^^ 



/ 



Fig. 9. — The Swan, Vega, the Eagle. 

which hangs 69,000,000,000^000 kilometers (42,000,- 
000,000,000 miles) above our Earth, is the nearest of 
all the stars to the skies of Europe. 

Not far oflp is the fine Eagle, w^hich spreads its wings 
in the Milky Way, and in which the star Altair, a, of 
first magnitude, is situated between its two satellites, 
/3 and 7. 

The Constellation of Hercules, toward which the 
41 



ASTRONOMY FOR AMATEURS 

motions of the Sun are impelling us, with all the planets 
of its system, is near the Lyre, its principal stars can 
be recognized inside the triangle formed by the Pole- 
Star, Arcturus, and Vega. 

All the Constellations described above belong to the 
Northern Hemisphere. Those nearest the pole are called 
circumpolar. They revolve round the pole in twenty- 
four hours. 

Having now learned the Northern Heavens, we 
must come back to the Sun, which we have left behind 
us. The Earth revolves round him in a year, and 
in consequence he seems to revolve round us, sweeping 
through a vast circle of the celestial sphere. In each 
year, at the same period, he passes the same points of the 
Heavens, in front of the same constellations, which 
are rendered invisible by his light. We know that the 
stars are at a fixed position from the Earth, whatever 
their distance, and that if we do not see them at noon 
as at midnight, it is simply because they are extin- 
guished by the dazzling light of the orb of day. With 
the aid of a telescope it is always possible to see the 
more brilliant of them. 

The Zodiac is the zone of stars traversed by the Sun 
in the course of a year. This word is derived from the 
Greek Zodiakos^ which signifies *^ animal," and this 
etymology arose because most of the figures traced 

42 



THE CONSTELLATIONS 

on this belt of stars represent animals. The belt is 
divided into twelve parts that are called the twelve 
Signs of the Zodiac, also named by the ancients the 
*' Houses of the Sun/' since the Sun visits one of them 
in each month. These are the signs, with the primitive 
characters that distinguish them: the Ram T, the 
Bull 8, the Twins n, the Crab 25, the Lion S\.y the 
Virgin Wd, the Balance =^, the Scorpion ttl , the Archer f , 
the Goat YS, the Water-Carrier ^, the Fishes X. The 
sign T represents the horns of the Ram, ^ the head of 
the Bull, and so on. 

If you will now follow me into the Houses of the Sun 
you will readily recognize them again, provided you 
have a clear picture of the principal stars of the North- 
ern Heavens. First, you see the Ram, the initial sign 
of the Zodiac; because at the epoch at which the actual 
Zodiac was fixed, the Sun entered this sign at the vernal 
equinox, and the equator crossed the ecliptic at this 
point. This constellation, in which the horns of the 
Ram (third magnitude) are the brightest, is situated 
between Andromeda and the Pleiades. Two thousand 
years ago, the Ram was regarded as the symbol of 
spring ; but owing to the secular movement of the pre- 
cession of the equinoxes, the Sun is no longer there on 
March 21 : he is in the Fishes. 

To the left, or east of the Ram, we find the Bull, 

43 



ASTRONOMY FOR AMATEURS 

the head of which forms a triangle in which burns 
Aldebaran, of first magnitude, a magnificent red star 
that marks the right eye; and the Hyades, scintillat- 
ing pale and trembling, on its forehead. The timid 
Pleiades, as we have seen, veil themselves on the shoul- 
der of the Bull — a captivating cluster, of which six stars 
can be counted with the unaided eye, while several 
hundred are discovered with the telescope. 

Next the Twins. They are easily recognized by 
the two fine stars, a and /3, of first magnitude, which 
mark their heads, and immortalize Castor and Pollux, 
the sons of Jupiter, celebrated for their indissoluble 
friendship. 

Cancer, the Crab, is the least important sign of the 
Zodiac. It is distinguished only by five stars of fourth 
and fifth magnitudes, situated below the Hne of Castor 
and Pollux, and by a pale cluster called Praesepe, the 
Beehive. 

The Lion next approaches, superb in his majesty. 
At his heart is a gorgeous star of first magnitude, a or 
Regulus. This figure forms a grand trapezium of four 
stars on the celestial sphere. 

The Virgin exhibits a splendid star of first magnitude; 
this is Spica, which with Regulus and Arcturus, form 
a triangle by which this constellation can be recog- 
nized. 

44 



THE CONSTELLATIONS 

The Balance follows the Virgin. Its scales, marked 
by two stars of second magnitude, are situated a little 
to the East of Spica. 

We next come to the eighth constellation of the 
Zodiac, which is one of the most beautiful of this belt 
of stars. Antares, a red star of first magnitude, occupies 
the heart of the venomous and accursed Scorpion. It 
is situated on the prolongation of a line joining Regulus 
to Spica, and forms with Vega of the Lyre, and Arcturus 
of the Herdsman, a great isosceles triangle, of which 
this latter star is the apex. 

The Scorpion, held to be a sign of ill luck, has been 
prejudicial to the Archer, which follows it, and traces 
an oblique trapezium in the sky, a little to the east of 
Antares. These two southernmost constellations never 
rise much above the horizon for France and England. 
In fable, the Archer is Chiron, the preceptor of Jason, 
Achilles and /Esculapius. 

Capricorn lies to the south of Altair, on the pro- 
longation of a line from the Lyre to the Eagle. It is 
hardly noticeable save for the stars a and ^ of third 
magnitude, which scintillate on its forehead. 

The Water-Carrier pours his streams toward the 
horizon. He is not rich in stars, exhibiting only three 
of third magnitude that form a very flattened triangle. 

Lastly the Fishes, concluding sign of the Zodiac, are 

45 



ASTRONOMY FOR AMATEURS 

found to the south of Andromeda and Pegasus. Save 
for a, of third magnitude, this constellation consists 
of small stars that are hardly visible. 

These tv^elve zodiacal constellations vs^ill be recog- 
nized on examining the chart (Figs. lo— ii). 

We must now visit the stars of the Southern Heav- 
ens, some of w^hich are equally deserving of admiration. 

It should in the first place be noted that the signs 









• 




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Fph. 1 Janiiani 1 


D,-ce abcr 1 -N 


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V^DELPHINUS ^ 

it ^Altair ^ 


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^ if.Arcturus 

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it 
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Begulus ^ 


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SAGITTARIUS^ SCORPIO 




^Spica 


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CENTAURUS 


^ CORVUS 


HYDRA ^ 


. J 



Fig. io. — The Constellations of the Zodiac: summer and autumn; 
Capricorn, Archer, Scorpion, Balance, Virgin, Lion. 



of the Zodiac and the Southern Constellations are not, 
like those w^hich are circumpolar, perpetually visible 
at all periods of the year. Their visibility depends on 
the time of year and the hour of the night. "^ 

In order to admire the fine constellations of the 
North, as described above, v^e have only to open our 

* All the stars visible at any hour during the year can easily be found with 
the help of the author's Planisphere mobile. 

46 



THE CONSTELLATIONS 

windows on a clear summer's evening, or walk round 
the garden in the mysterious light of these inaccessible 
suns, while we look up at the immense fields in which 
each star is like the head of a celestial spear. 

But the summer is over, autumn is upon us, and 
then, too soon, comes winter clothed in hoarfrost. 
The days are short and cold, dark and dreary; but as 
a compensation the night is much longer, and adorns 



j^cheat 




SiriusH' * 

Fig. II. — The Constellations of the Zodiac : winter and spring ; Crab, 
Twins, Bull, Ram, Fishes, Water-Carrier. 



herself with her most beautiful jewels, offering us the 
contemplation of her inexhaustible treasures. 

First, let us do homage to the magnificent Orion, 
most splendid of all the constellations: he advances like 
a colossal giant, and confronts the Bull. 

This constellation appears about midnight in No- 
vember, in the south-eastern Heavens; toward eleven 

47 



ASTRONOMY FOR AMATEURS 

o'clock in December and January, due south; about 
ten in February, in the south-east; about nine in March, 
and about eight in April, in the west; and then sets 
below our horizon. 




Fig. 12. — Orion and his celestial companions. 



It is indisputably the most striking figure in the sky, 
and with the Great Bear, the most ancient in history, 
the first that was noticed : both are referred to in the an- 
cient texts of China, Chaldea, and Egypt. 

48 



THE CONSTELLATIONS 

Eight principal stars delineate its outline; two are of 
the first magnitude, five of the second, and one of the 
third (Fig. 12). The most brilliant are Betelgeuse (a) and 
Rigel (/3) : the former marking the right shoulder of the 
Colossus as it faces us; the second the left foot. The star 
on the left shoulder is 7 or Bellatrix, of second magni- 
tude; that of the right foot, ^, is almost of the third. 
Three stars of second magnitude placed obliquely at 
equal distances from each other, the first or highest 
of which marks the position of the equatorial line, 
indicate the Belt or Girdle. These stars, known as the 
Three Kings, and by country people as the Rake, as- 
sist greatly in the recognition of this fine constellation. 

A little below the second star of the Belt, a large 
white patch, like a band of fog, the apparent dimensions 
of which are equal to that of the lunar disk, is visible 
to the unaided eye: this is the Nebula of Orion, one of 
the most magnificent in the entire Heavens. It was 
discovered in 1656 by Huyghens, who counted twelve stars 
in the pale cloud. Since that date it has been constantly 
studied and photographed by its many admirers, while 
the giant eye of the telescope discovers in it to-day 
an innumerable multitude of little stars which reveal 
the existence of an entire universe in this region. 

Orion is not merely the most imposing of the celestial 
figures; it is also the richest in sidereal wonders. Among 

49 



ASTRONOMY FOR AMATEURS 

these, it exhibits the most complex of all the multiple 
systems known to us: that of the star situated in the 
celebrated nebula just mentioned. This marvelous 
star, viewed through a powerful telescope, breaks up 
into six suns, forming a most remarkable stellar group. 

This region is altogether one of the most brilliant in 
the entire firmament. We must no longer postpone our 
homage to the brightest star in the sky, the magnificent 
Sirius, which shines on the left below Orion: it returns 
every year toward the end of November. This mar- 
velous star, of dazzling brilliancy, is the first, a, in the 
constellation of the Great Dog, which forms a quadri- 
lateral, the base of which is adjacent to a triangle 
erected from the horizon. 

When astronomers first endeavored to determine the 
distance of the stars, Sirius, which attracted all eyes 
to its burning fires, was the particular object of attention. 
After long observation, they succeeded in determin- 
ing its distance as 92 trillion kilometers (57 trillion 
miles). Light, that radiates through space at a velocity 
of 300,000 kilometers (186,000 miles) per second, takes 
no less than ten years to reach us from this sun, which, 
nevertheless, is one of our neighbors. 

The Little Dog, in which Procyon (a, of first magni- 
tude) shines out, is above its big brother. With the ex- 
ception of a, it has no bright stars. 

SO 



THE CONSTELLATIONS 

Lastly, toward the southern horizon, we must notice 
the Hydra, Eridanus, the Whale, the Southern Fish, the 









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Ship, and the Centaur. This last constellation, while 
invisible to our latitudes, contains the star that is 
5 51 



ASTRONOMY FOR AMATEURS 



nearest to the Earth, a, of first magnitude, the dis- 
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The feet of the Centaur touch the Southern Cross, 
which is always invisible to us, and a little farther 

52 



THE CONSTELLATIONS 

down the Southern Pole reigns over the icy desert of 
the antarctic regions. 




In order to complete the preceding descriptions, we 
subjoin four charts representing the aspect of the starry 

53 



ASTRONOMY FOR AMATEURS 

heavens during the evenings of winter, spring, summer, 
and autumn. To make use of these, we must suppose 




them to be placed above our heads, the center marking 
the zenith, and the sky descending all round to the hori- 

54 



THE CONSTELLATIONS 

zon. The horizon, therefore, bounds these panoramas. 
Turning the chart in any direction, and looking at it 
from north, south, east, or west, we find all the prin- 
cipal stars. The first map (Fig. 13) represents the sky 
in winter (January) at 8 p. m.; the second, in spring 
(April) at 9 p. m.; the third, in summer (July) at the 
same hour; the fourth, the sky in autumn (October) 
at the same time. 

And so, at little cost, we have made one of the grand- 
est and most beautiful journeys conceivable. We now 
have a new country, or, better, have learned to see and 
know our own country, for since the Earth is a planet 
we must all be citizens of the Heavens before we can 
belong to such or such a nation of our lilliputian world. 

We must now study this sublime spectacle of the 
Heavens in detail. 



55 



CHAPTER III 

THE STARS, SUNS OF THE INFINITE 

A Journey through Space 

We have seen from the foregoing summary of the 
principal Constellations that there is great diversity in 
the brightness of the stars, and that while our eyes are 
dazzled with the brilliancy of certain orbs, others, on the 
contrary, sparkle modestly in the azure depths of the 
night, and are hardly perceptible to the eye that seeks 
to plumb the abysses of Immensity. 

We have appended the word ''magnitude" to the 
names of certain stars, and the reader might imagine 
this to bear some relation to the volume of the orb. 
But this is not the case. 

To facilitate the observation of stars of varying bril- 
liancy, they have been classified in order of magnitude, 
according to their apparent brightness, and since the 
dimensions of these distant suns are almost wholly un- 
known to us, the most luminous stars were naturally 
denoted as of first magnitude, those which were a little 
less bright of the second, and so on. But in reality 

56 



THE STARS, SUNS OF THE INFINITE 

this word ** magnitude'' is quite erroneous, for it bears 
no relation to the mass of the stars, divided thus at an 
epoch when it was supposed that the most brilHant 
must be the largest. It simply indicates the apparent 
brightness of a star, the real brilliancy depending on its 
dimensions, its intrinsic light, and its distance from 
our planet. 

And now to make some comparison between the 
different orders. Throughout the entire firmament, 
only nineteen stars of first magnitude are discover- 
able. And, strictly speaking, the last of this series 
might just as well be noted of ^'second magnitude," 
while the first of the second series might be added to 
the list of stars of the ** first order.'' But in order to 
form classes distinct from one another, some limit has 
to be adopted, and it was determined that the first series 
should include only the following stars, the most lumi- 
nous in the Heavens, which are subjoined in order of 
decreasing brilliancy. 



STARS OF THE FIRST MAGNITUDE 

Sirius, or a of the Great Dog. 
Canopus, or a of the Ship. 
Capella, or a of the Charioteer. 
Arcturus, or a of the Herdsman. 
Vega, or a of the Lyre. 

57 



ASTRONOMY FOR AMATEURS 

6. Proxima, or a of the Centaun 

7. Rigel, or fS of Orion. 

8. Achernar, or a of Eridanus. 

9. Procyon, or a of the Little Dog. 

10. yS of the Centaur. 

1 1 . Betelgeuse, or a of Orion. 

12. Altair, or a of the Eagle. 

13. a of the Southern Cross. 

14. Aldebaran, or a of the Bull. 

15. Spica, or a of the Virgin. 

16. Antares, or a of the Scorpion. 

17. Pollux, or /3 of the Twins. 

18. Regulus, or a of the Lion. 

19. Fomalhaut, or a of the Southern Fish. 

THE STARS OF THE SECOND MAGNITUDE 

Then come the stars of the second magnitude, of 
which there are fifty-nine. The stars of the Great 
Bear (with the exception of S, which is of third magni- 
tude), the Pole-Star, the chief stars in Orion (after Rigel 
and Betelgeuse), of the Lion, of Pegasus, of Andromeda, 
of Cassiopeia, are of this order. These, with the former, 
constitute the principal outlines of the constellations 
visible to us. 

Then follow the third and fourth magnitudes, and 
so on. 



THE STARS, SUNS OF THE INFINITE 

The following table gives a summary of the series, 
down to the sixth magnitude, which is the limit of 
visibility for the unaided human eye* 
19 stars of first magnitude, 
59 of second magnitude. 
182 of third magnitude. 
530 of fourth magnitude. 
1,600 of fifth magnitude. 
4,800 of sixth magnitude. 
This makes a total of some seven thousand stars 
visible to the unaided eye. It will be seen that each 
series is, roughly speaking, three times as populated as 
that preceding it; consequently, if we multiply the num- 
ber of any class by three, we obtain the approximate 
number of stars that make up the class succeeding it. 

Seven thousand stars! It is an imposing figure, when 
one reflects that all these lucid points are suns, as 
enormous as they are potent, as incandescent as our own 
(which exceeds the volume of the Earth by more than a 
million times), distant centers of light and heat, exerting 
their attraction on unknown systems. And yet it is gen- 
erally imagined that millions of stars are visible in the 
firmament. This is an illusion; even the best vision is 
unable to distinguish stars below the sixth magnitude, 
and ordinary sight is far from discovering all of these. 
Again, seven thousand stars for the whole Heavens 

59 



ASTRONOMY FOR AMATEURS 

makes only three thousand five hundred for half the 
sky. And we can only see one celestial hemisphere 
at a time. Moreover, toward the horizon, the vapor 
of the atmosphere veils the little stars of sixth magni- 
tude. In reality, we never see at a given moment 
more than three thousand stars. This number is below 
that of the population of a small town. 

But celestial space is unlimited, and we must not 
suppose that these seven thousand stars that fascinate 
our eyes and enrich our Heavens, without which our 
nights would be black, dark, and empty,* comprise 
the whole of Creation. They only represent the vesti- 
bule of the temple. 

Where our vision is arrested, a larger, more powerful 
eye, that is developing from century to century, plunges 
its analyzing gaze into the abysses, and reflects back 
to the insatiable curiosity of science the light of the 
innumerable suns that it discovers. This eye is the lens 
of the optical instruments. Even opera-glasses disclose 
stars of the seventh magnitude. A small astronomical 
objective penetrates to the eighth and ninth orders. 
More powerful instruments attain the tenth. The 

* Let It be remarked in passing that the stars might be much farther off 
than they are, and invisible to our eyes 5 the Heavens would then assume the 
aspect of an absolutely empty space, the moon and planets alone remaining. 

60 



THE STARS, SUNS OF THE INFINITE 



Heavens are progressively transformed to the eye of the 
astronomer, and soon he is able to reckon hundreds of 
thousands of orbs in the night. The evolution con- 
tinues; the power of the instrument is developed; and 
the stars of the eleventh and twelfth magnitudes are 
discovered successively, and together number four 
millions. Then follow the thirteenth, fourteenth, and 
jfifteenth magnitudes. This is the sequence: 

yth magnitude 13,000. 

8th '' 40,000. 

9th *' 120,000. 

loth " 380,000. 

nth " 1,000,000. 

I2th " 3,000,000. 

13th " 9,000,000. 

14th " 27,000,000. 

15th " 80,000,000. 

Accordingly, the most powerful telescopes of the 
day, reenforced by celestial photography, can bring a 
stream of more than 120 millions of stars into the scope 
of our vision. 

The photographic map of the Heavens now being 
executed comprises the first fourteen magnitudes, and 
will give the precise position of some 40,000,000 stars, 
distributed over 22,054 sheets, forming a sphere 3 
meters 44 centimeters in diameter. 

61 



ASTRONOMY FOR AMATEURS 

The boldest imagination is overwhelmed by these 
figures, and fails to picture such millions of suns — 
formidable and burning globes that roll through space, 
sweeping their systems along w^th them. What fur- 
naces are there! what unknown lives! w^hat vast im- 
mensities ! 

And again, w^hat enormous distances must separate 
the stars, to admit of their free revolution in the ether! 
In what abysses, at what a distance from our terrestrial 
atom, must these magnificent and dazzling Suns pursue 
the paths traced for them by Destiny! 

If all the stars radiated an equal light, their distances 
might be calculated on the principle that an object ap- 
pears smaller in proportion to its distance. But this 
equality does not exist. The suns were not all cast 
in the same mold. 

Indeed, the stars differ widely in size and brightness, 
and the distances that have been measured show that 
the most brilliant are not the nearest. They are scat- 
tered through Space at all distances. 

Among the nearer stars of which it has been found 
possible to calculate the distance, some are found to be 
of the fourth, fifth, sixth, seventh, eighth, and even ninth 
magnitudes, proving that the most brilliant are not 
always the least distant. 

62 



THE STARS, SUNS OF THE INFINITE 

For the rest, among the beautiful and shining stars 
with which we made acquaintance in the last chapter 
may be cited Sirius, which at a distance of 92 trillion 
kilometers (57 trillion miles) from here still dazzles us 
with its burning fires; Procyon or a of the Little Dog, 
as remote as 112 trillion kilometers (69^ triUion miles); 
Altair of the Eagle, at 160 trillion kilometers (99 trillion 
miles); the white Vega, at 204 trillion kilometers (126^ 
trilHon miles); Capella, at 276 (171 trillion miles); 
and the Pole-Star at 344 trillion kilometers (213^ 
trillion miles). The light that flies through Space at 
a velocity of 300,000 kilometers (186,000 miles) per 
second, takes thirty-six years and a half to reach us 
from this distant sun: i, e,^ the luminous ray we are 
now receiving from Polaris has been traveling for 
more than the third of a century. When you, gentle 
reader, were born, the ray that arrives to-day from the 
Pole-Star was already speeding on its way. In the first 
second after it had started it traveled 300,000 kilo- 
meters ; in the second it added another 300,000 which 
at once makes 600,000 kilometers; add another 300,- 
000 kilometers for the third second, and so on during 
the thirty-six years and a half. 

If we tried to arrange the number 300,000 (which 
represents the distance accomplished in one second) in 
superposed rows, as if for an addition sum, as many 

63 



ASTRONOMY FOR AMATEURS 

times as is necessary to obtain the distance that sepa- 
rates the Pole-Star from our Earth, the necessary opera- 
tion would comprise 1,151,064,000 rows, and the sheet 
of paper required for the setting out of such a sum 
would measure approximately 11,510 kilometers (about 
7,000 miles), /. ^., almost the diameter of our terrestrial 
globe, or about four times the distance from Paris to 
Moscow ! 

Is it not impossible to realize that our Sun, with its 
entire system, is lost in the Heavens at such a distance 
from his peers in Space r At the distance of the least 
remote of the stars he would appear as one of the 
smallest. 

The nearest star to us is a of the Centaur, of first 
magnitude, a neighbor of the South Pole, invisible 
in our latitudes. Its distance is 275,000 radii of the 
terrestrial orbit, i, f., 275,000 times 149 million kilo- 
meters, which gives 41 trillions, or 41,000 milliards of 
kilometers (= 25^ trillion miles). [A milliard = 1,000 
millions, the French billion. A trillion == 1,000 mil- 
liards, or a million millions, the English billion. The 
French nomenclature has been retained by the trans- 
lator.] At a speed of 300,000 kilometers (186,000 miles) 
per second the light takes four years to come from 
thence. It is a fine double star. 

64 



THE STARS, SUNS OF THE INFINITE 

The next nearest star after this is a Httle orb in- 
visible to the unaided eye. It has no name, and stands 
as No. 21,185 in the Catalogue of Lalande. It almost 
attains the seventh magnitude (6.8). Its distance is 
64 trillion kilometers (39/^ trillion miles). 

The third of which the distance has been measured 
is the small star in Cygnus, already referred to in Chap- 
ter II, in describing the Constellations. Its distance is 
69 trillion kilometers (42^ trillion miles). This, too, 
is a double star. The light takes seven years to 
reach us. 

As w^e have seen, the fine stars Sirius, Procyon, 
Aldebaran, Altair, Vega, and Capella are more remote. 

Our solar system is thus very isolated in the vastness 
of Infinitude. The latest known planet of our system, 
Neptune, performs its revolutions in space at 4 milliards, 
470 million kilometers (2,771,400,000 miles) from our 
Sun. Even this is a respectable distance! But beyond 
this world, an immense gulf, almost a void abyss, ex- 
tends to the nearest star, a of the Centaur. Between 
Neptune and Centauris there is no star to cheer the 
black and cold solitude of the immense vacuum. One 
or two unknown planets, some wandering comets, and 
swarms of meteors, doubtless traverse those unknown 
spaces, but all invisible to us. 

Later on we will discuss the methods that have been 

6s 



ASTRONOMY FOR AMATEURS 

employed in measuring these distances. Let us now 
continue our description. 



Now that we have some notion of the distance of 
the stars we must approach them with the telescope, and 
compare them one with another. 

Let us, for example, get close to Sirius: in this star 
we admire a sun that is several times heavier than our 
own, and of much greater mass, accompanied by a 
second sun that revolves round it in fifty years. Its 
light is exceedingly white, and it notably burns with 
hydrogen flames, like Vega and Altair. 

Now let us approach Arcturus, Capella, Aldebaran: 
these are yellow stars with golden rays, like our Sun, and 
the vapor of iron, of sodium, and of many other metals 
can be identified in their spectrum. These stars are 
older than the first, and the ruddy ones, such as An- 
tares, Betelgeuse, a of Hercules, are still older; several 
of them are variable, and are on their way to final ex- 
tinction. 

The Heavens aflFord us a perennial store of treasure, 
wherein the thinker, poet or artist can find inexhaustible 
subjects of contemplation. 

You have heard of the celestial jewels, the diamonds, 
rubies, emeralds, sapphires, topazes, and other precious 

66 



THE STARS, SUNS OF THE INFINITE 

stones of the sidereal casket. These marvels are met 
with especially among the double stars. 

Our Sun, white and solitary, gives no idea of the 
real aspect of some of its brothers in Infinitude. There 
are as many different types as there are suns! 

Stars, you will think, are like individuals: each has 
its distinct characteristics: no two are comparable. 
And indeed this reflection is justified. While human 
vanity does homage to Phoebus, divine King of the 
Heavens, other suns of still greater magnificence form 
groups of two or three splendid orbs, which roll the 
prodigious combinations of their double, triple, or 
multiple systems through space, pouring on to the worlds 
that accompany them a flood of changing light, now 
blue, now red, now violet, etc. 

In the inexhaustible variety of Creation there exist 
Suns that are united in pairs, bound by a common 
destiny, cradled in the same attraction, and often colored 
in the most delicate and entrancing shades conceivable. 
Here will be a dazzling ruby, its glowing color shedding 
joy; there a deep blue sapphire of tender tone; beyond, 
the finest emeralds, hue of hope. Diamonds of translu- 
cent purity and whiteness sparkle from the abvss, and 
shed their penetrating light into the vast space. What 
splendors are scattered broadcast over the sky! what 
profusion! 

6 67 



ASTRONOMY FOR AMATEURS 

To the naked eye, the groups appear like ordinary 
stars, mere luminous points of greater or less brilliancy; 
but the telescope soon discovers the beauty of these 
systems; the star is duplicated into two distinct suns, 
in close proximity. These groups of two or several 
suns are not merely due to an effect of perspective — z. e,^ 
the presence of two or more stars in our line of sight; 
as a rule they constitute real physical systems, and these 
suns, associated in a common lot, rotate round one 
another in a more or less rapid period, that varies for 
each system. 

One of the most splendid of these double stars, and 
at the same time one of the easiest to perceive, is ^ in 
the Great Bear, or Mizar, mentioned above in de- 
scribing this constellation. It has no contrasting colors, 
but exactly resembles tw4n diamonds of the finest 
water, which fascinate the gaze, even through a small 
objective. 

Its components are of the second and fourth magni- 
tudes, their distance = 14'^*. Some idea of their ap- 
pearance in a small telescope m.ay be obtained from the 
subjoined figure (Fig. 17). 

Another very brilliant pair is Castor. Magnitudes 

* 14" nr 14 seconds of arc. One second of the circle is an exceedingly minute 
quantity. It is l millimeter seen at a distance of 206 meters. One millimeter 
seen at a distance of 20 m. 62 = 10 sees. These values are invisible to the 
unaided eye. 

68 



THE STARS, SUNS OF THE INFINITE 

second and third. Distance '5'''6. Very easy to observe. 
7 in the Virgin resolves into tw^o splendid diamonds 
of third magnitude. Distance, *5''*o. Another double 
star is 7 of the Ram, of fourth magnitude. Distance, 'S'^'Q. 
And here are tv^o that are even more curious by 
reason of their coloring: 7 in Andromeda, composed 




Fig. 17. — The double star Mizar. 

of a fine orange star, and one emerald-green, v^hich 
again is accompanied by a tiny comrade of the deepest 
blue. This group in a good telescope is most attractive. 
Magnitudes, second and fifth. Distance, lo'^ 

^ of the Sw^an, or Albireo, referred to in the last 
chapter, has been analyzed into two stars: one golden- 

69 



ASTRONOMY FOR AMATEURS 

yellow, the other sapphire. Magnitudes, third and 
fifth. Distance, 34'^ a of the Greyhounds, known 
also as the Heart of Charles II, is golden-yellow 
and lilac. Magnitudes, third and fifth. Distance 

20^* 

a of Hercules revolves a splendid emerald and a 
ruby in the skies; ^ of the Lyre exhibits a yellow and a 
green star; Rigel, an electric sun, and a small sapphire; 
Antares is ruddy and emerald-green; rf of Perseus re- 
solves into a burning red star, and one smaller that is 
deep blue, and so on. 

These exquisite double stars revolve in gracious and 
splendid couples around one another, as m some majestic 
valse, marrying their multicolored fires in the midst 
of the starry firmament. 

Here, we constantly receive a pure and dazzling 
white light from our burning luminary. Its ray, indeed, 
contains the potentiality of every conceivable color, 
but picture the fantastic illumination of the worlds that 
gravitate round these multiple and colored suns as 
they shed floods of blue and roseate, red, or orange 
light around them! What a fairy spectacle must life 
present upon these distant universes! 

■^ These fine double stars can be observed with the help of the smallest tele- 
scope. 

70 



THE STARS, SUNS OF THE INFINITE 

Let us suppose that we inhabit a planet illuminated 
by two suns, one blue, the other red. 

It is morning. The sapphire sun climbs slowly 
up the Heavens, coloring the atmosphere with a somber 
and almost melancholy hue. The blue disk attains 
the zenith, and is beginning its descent toward the 
West, when the East lights up with the flames of a scar- 
let sun, which in its turn ascends the heights of the 
firmament. The West is plunged in the penumbra 
of the rays of the blue sun, while the East is illuminated 
with the purple and burning rays of the ruby orb. 

The first sun is setting when the second noon shines 
for the inhabitants of this strange world. But the red 
sun, too, accomplishes the law of its destiny. Hardly 
has it disappeared in the conflagration of its last rays, 
with which the West is flushed, when the blue orb 
reappears on the opposite side, shedding a pale azure 
light upon the world it illuminates, which knows no 
night. And thus these two suns fraternize in the 
Heavens over the common task of renewing a thousand 
eflTects of extra-terrestrial light for the globes that are 
subject to their variations. 

Scarlet, indigo, green, and golden suns; pearly and 
multicolored Moons; are these not fairy visions, dazzling 
to our poor sight, condemned while here below to see 
and know but one white Sun ? 

71 



ASTRONOMY FOR AMATEURS 

As we have learned, there are not only double, but 
triple, and also multiple stars. One of the finest ter- 
nary systems is that of 7 in Andromeda, above mentioned. 
Its large star is orange, its second green, its third blue, 
but the two last are in close juxtaposition, and a powerful 
telescope is needed to separate them. A triple star more 




Fig. 18. — Triple star I in Cancer. 

easy to observe is ^ of Cancer, composed of three orbs 
of fifth magnitude, at a distance of i'^ and 5''; the first 
two revolve round their common center of gravity in 
fifty-nine years, the third takes over three hundred 
years. The preceding figure shows this system in a 
fairly powerful objective (Fig. 18). 

72 



THE STARS, SUNS OF THE INFINITE 

In the L\Te, a little above the dazzling Vega, € is 
of fourth magnitude, which seems a little elongated 
to the unaided eve, and can even be analyzed into two 
contiguous stars hv verv sharp sight. But on examining 
this attractive pair with a small glass, it is further 
obvious that each of these stars is double; so that they 




Fig. 19. — Quadruple star e of the Lyre. 

form a splendid quadruple svstem of two couples fFig. 
19): one of fifth and a half and sixth magnitudes, at a 
distance of *2^^*4, the other of sixth and seventh, '^'^'2 
distant. The distance between the two pairs is 207''. 
In speaking of Orion, we referred to the marvelous 
star 0^ situated in the no less famous Nebula, below 

73 



ASTRONOMY FOR AMATEURS 

the Belt; this star forms a dazzling sextuple system, in 
the very heart of the nebula (Fig. 20). How different 
to our Sun, sailing through Space in modest isola- 
tion ! 

Be it noted that all these stars are animated by 
prodigious motions that impel them in every direction. 




Fig. 20. — Sextuple star d in the Nebula of Orion. 

There are no fixed stars. On every side throughout 
Infinity, the burning suns — enormous globes, blazing 
centers of light and heat — are flying at giddy speed 
toward an unknown goal, traversing millions of miles 
each day, crossing century by century such vast spaces 
as are inconceivable to the human intellect. 

74 



THE STARS, SUNS OF THE INFINITE 

If the stars appear motionless to us, it is because 
they are so remote, their secular movements being only 
manifested on the celestial sphere by imperceptible 
displacements. But in reality these suns are in per- 
petual commotion in the abysses of the Heavens, v^hich 
they quicken with an extraordinary animation. 

These perpetual and cumulative motions must 
eventually modify the aspect of the Constellations: 
but these changes v^ill only take effect very slowly; and 
for thousands and thousands of years longer the heroes 
and heroines of mythology will keep their respective 
places in the Heavens, and reign undisturbed beneath 
the starry vault. 

Examination of these star motions reveals the fact 
that our Sun is plunging with all his system (the Earth 
included) toward the Constellation of Hercules. We 
are changing our position every moment: in an hour 
we shall be 70,000 kilometers (43,500 miles) farther 
than we are at present. The Sun and the Earth will 
never again traverse the space they have just left, and 
which they have deserted forever. 

And here let us pause for an instant to consider the 
variable stars. Our Sun, which is constant and uniform 
in its light, does not set the type of all the stars. A 
great number of them are variable — either periodically, 
in regular cycles — or irregularly, 

IS 



ASTRONOMY FOR AMATEURS 

We are already acquainted with the variations of 
Algol, in Perseus, due to its partial eclipse by a dark 
globe gravitating in the line of our vision. There are 
several others of the same type: these are not, properly 
speaking, variable stars. But there are many others 
the intrinsic light of which undergoes actual variations. 

In order to realize this, let us imagine that our Earth 
belongs to such a sun, for example, to a star in the 
southern constellation of the Whale, indicated by the 
letter o, which has been named the ''wonderful" (Mira 
Ceti). Our new sun is shining to-day with a dazzling 
light, shedding the gladness of his joyous beams upon 
nature and in our hearts. For two months we admire 
the superb orb, sparkling in the azure illuminated 
with its radiance. Then of a sudden, its light fades, 
and diminishes in intensity, though the sky remains 
clear. Imperceptibly, our fine sun darkens; the at- 
mosphere becomes sad and dull, there is an anticipation 
of universal death. For five long months our world 
is plunged in a kind of penumbra; all nature is saddened 
in the general woe. 

But while we are bewailing the cruelty of our lot, 
our cherished luminary revives. The intensity of its 
light increases slowly. Its brilliancy augments, and 
finally, at the end of three months, it has recovered its 
former splendors, and showers its bright beams upon our 

76 



THE STARS, SUNS OF THE INFINITE 

world, flooding it with joy. But — we must not rejoice 
too quickly! This splendid blaze will not endure. The 
flaming star will pale once more; fade back to its mini- 
mum; and then again revive. Such is the nature of this 
capricious sun. It varies in three hundred and thirty- 
one days, and from yellow at the maximum, turns red 
at the minimum. This star, Mira Ceti, which is one 
of the most curious of its type, varies from the second 
to the ninth magnitudes: we cite it as one example; 
hundreds of others might be instanced. 

Thus the sky is no black curtain dotted with brilliant 
points, no empty desert, silent and monotonous. It 
is a prodigious theater on which the most fantastic plays 
are continually being acted. Only — there are no 
spectators. 

Again, we must note the temporary stars, which shine 
for a certain time, and then die out rapidly. Such 
was the star in Cassiopeia, in 1572, the light of which 
exceeded Sirius in its visibility in full daylight, burn- 
ing for five months with unparalleled splendor, domi- 
nating all other stars of first magnitude; after which it 
died out gradually, disappearing at the end of seventeen 
months, to the terror of the peoples, who saw in it the 
harbinger of the world's end: that of 1604, in the Con- 
stellation of the Serpent, which shone for a year; of 
1866, of second magnitude, in the Northern Crown, 

77- 



ASTRONOMY FOR AMATEURS 

which appeared for a few weeks only; of 1876, in the 
Swan; of 1885, in the Nebula of Andromeda; of 1891, 
in the Charioteer; and quite recently, of 1901, in Perseus. 
These temporary stars, which appear spontaneously 
to the observers on the Earth, and quickly vanish again, 
are doubtless due to collisions, conflagrations, or celestial 
cataclysms. But we only see them long after the epoch 
at which the phenomena occurred, years upon years, and 
centuries ago. For instance, the conflagration photo- 
graphed by the author in 1901, in Perseus, must have 
occurred in the time of Queen Elizabeth. It has taken 
all this time for the rays of light to reach us. 

The Heavens are full of surprises, on which we can 
bestow but a fleeting glance within these limits. They 
present a field of infinite variety. 

Who has not noticed the Milky Way, the pale belt 
that traverses the entire firmament and is so luminous 
on clear evenings in the Constellations of the Swan and 
the Lyre ? It is indeed a swarm of stars. Each is in- 
dividually too small to excite our retina, but as a whole, 
curiously enough, they are perfectly visible. With 
opera-glasses we divine the starry constitution: a small 
telescope shows us marvels. Eighteen millions of stars 
were counted there with the gauges of William Herschel. 

Now this Milky Way is a symbol, not of the Universe, 

78 



THE STARS, SUNS OF THE INFINITE 

but of the Universes that succeed each other through 
the vast spaces to Infinity. 

Our Sun is a star of the Milky Way. It surrounds 
us Hke a great circle, and if the Earth were transparent^ 
we should see it pass beneath our feet as well as over 
our heads. It consists of a very considerable mass of 




Fig. 21. — The Star-Cluster in Hercules. 

star-clusters, varying greatly in extent and number, 
some projected in front of others, while the whole forms 
an agglomeration. 

Among this mass of star-groups, several thousands 
of which are already known to us, we will select one of 
the most curious, the Cluster in Hercules, which can be 

79 



ASTRONOMY FOR AMATEURS 

distinguished with the unaided eye, between the stars 
77 and ^ of that constellation. Many photographs of 
it have been taken in the author's observatory at Juvisy, 
showing some thousands of stars; and one of these is 
reproduced in the accompanying figure (Fig. 21). Is 
it not a veritable universe? 




Fig. 22. — The Star-Cluster in the Centaur. 

Another of the most beautiful, on account of its 
regularity, is that of the Centaur (Fig. 22). 

These groups often assume the most extraordinary 
shapes in the telescope, such as crowns, fishes, crabs, 
open mouths, birds with outspread wings, etc. 

We must also note the gaseous nehulcB^ universes in 
80 



THE STARS, SUNS OF THE INFINITE 

the making, e.g., the famous Nebula in Orion, of 
which we obtained some notion a while ago in connec- 




FiG. 23. — The Nebula in Andromeda. 
tion with its sextuple star: and also that in Andromeda 
(Fig- 23). 

81 



ASTRONOMY FOR AMATEURS 

Perhaps the most marvelous of all is that of the 
Greyhounds, which evolves in gigantic spirals round a 





; ;f . 


f/0--^M^^^'--''' 


--"W* 




i 


fl 'i S ^-^^^^v' ■ ■^'^■''- " ' ■ ■ 


1 ^ 


\^ ^ 


% ' 


'^\-'^^^^^:. r|| ^.;-''''lv' ■' 


yfe-v 


•>. .-, \. '^v^ .,.c- - „|Mii^ J^ ■( /W~ f' -V 


wk^' 


^■'"•■■. '^ '^****^\^^ ' > -3^ f 


.^k^* 


^^ "^^"^5^39^^ j^ ^^W M ' " 


/^ 


'v^'w ; • 3.X-«'''^^m ' ^- ■ ' --i " 




^^■■■''^y'^*^<^^'^:.^^^'>^^^^0i::'- ■■■ ' ' 




"-^ r': 



Fig. 24. — Nebula in the Greyhounds. 
dazzling focus, and then loses itself far off in the re- 
cesses of space. Fig. 24 gives a picture of it. 

82 



THE STARS, SUNS OF THE INFINITE 

Without going thus far, and penetrating into telescop- 
ic depths, my readers can get some notion of these star- 
clusters with the help of a small telescope or opera- 
glasses, or even with the unaided eye, by looking at the 
beautiful group of the Pleiades, already familiar to us 
on another page, and using it as a test of vision. The 
little map subjoined (Fig. 25) will be an assistance in 

Asterope I 

-^ Taygete 

^sterope II "At 



Pleione 



4t- 

Atlas 



Alcyone ' 



Maya 

M 



Fig. 25. — ^The Pleiades. 



. Cxleno 



^HJectre 



recognizing them, and in estimating their magnitudes, 
which are in the following order: 

Alcyone . 

Electra= , 



Atlas . . . 
Maia. . . 

Merope. 
Taygeta 

7 



3.0, 

4.5 
4.6 
5.0, 

5-5 
5.8 



83 



ASTRONOMY FOR AMATEURS 

Pleione 6.3, 

Celaeno „ 6.5. 

Asterope .6.8. 

Good eyes distinguish the first six, sharp sight de- 
tects the three others. 

In the times of the ancient Greeks, seven were ac- 
counted of equal brilliancy, and the poets related that 
the seventh star had fled at the time of the Trojan War. 
Ovid adds that she was mortified at not being embraced 
by a god, as were her six sisters. It is probable that only 
the best sight could then distinguish Pleione, as in our 
own day. The angular distance from Atlas to Pleione 
is 5'. 

The length of this republic, from Atlas and Pleione 
to Celaeno, is ^ /^^' of time, or 1° 6' of arc; the breadth, 
from Merope to Asterope, is 36'.* 

In the quadrilateral, the length from Alcyone to 
Electra is 36^, and the breadth from Merope to Maia 
25^ To us it appears as though, if the Full Moon were 
placed in front of this group of nine stars, she would 
cover it entirely, for to the naked eye she appears much 
larger than all the Pleiades together. But this is not sOo 
She only measures 31', less than half the distance from 
Atlas to Celaeno; she is hardly broader than the distance 

'-'' For the explanation of the angular distances of degrees, minutes, and sec- 
ondsj see Chapter XI, on Methods of Measurement. 

84 



THE STARS, SUNS OF THE INFINITE 

from Alcyone to Atlas, and could pass between Merope 
and Taygeta without touching either of these stars. 
This is a perennial and very curious optical illusion. 
When the Moon passes in front of the Pleiades, and 
occults them successively, it is hard to believe one's 




Fig. 26. — Occultation of the Pleiades by the Moon. 

eyes. The fact occurred, e, g., on July 23, 1897, during 
a fine occultation observed at the author's laboratory 
of Juvisy (Fig. 26). 

Photography here discovers to us, not 6, 9, I2, 15, 
or 20 stars, but hundreds and millions. 

85 



ASTRONOMY FOR AMATEURS 

These are the most briUiant flowers of the celestial 
garden. 

We, alas, can but glance at them rapidly. In con- 
templating them we are transported into immensities 
both of space and time, for the stellar periods measured 
by these distant universes often overpower in their mag- 
nitude the rapid years in which our terrestrial days are 




Fig. 27. — Stellar dial of the double star 7 of the Virgin. 

estimated. For instance, one of the double stars we 
spoke of above, 7 of the Virgin, sees its two components, 
translucent diamonds, revolve around their common 
center of gravity, in one hundred and eighty years. 
How many events took place in France, let us say, in a 
single year of this star! — The Regency, Louis XV, Louis 
XVI, the Revolution, Napoleon, Louis XVIII, Louis 

86 



THE STARS, SUNS OF THE INFINITE 

Philippe, the Second Republic, Napoleon III, the 
Franco-German War, the Third Republic. . . . What 
revolutions here, during a single year of this radiant 
pair! (Fig. 27.) 

But the pageant of the Heavens is too vast, too over- 
whelming. We must end our survey. 

Our Milky Way, vs^ith its millions of stars, represents 
for us only a portion of the Creation. The illimitable 
abysses of Infinitude are peopled by other universes as 
vast, as imposing, as our ow^n, which are renewed in all 
directions through the depths of Space to endless dis- 
tance. Where is our little Earth ? Where our Solar 
System ? We are fain to fold our wings, and return from 
the Immense and Infinite to our floating island. 



87 



CHAPTER IV 
OUR STAR THE SUN 

In the incessant agitation of daily life in which we 
are involved by the thousand superfluous wants of 
modern ** civilization/' one is prone to assume that ex- 
istence is complete only when it reckons to the good an 
incalculable number of petty incidents, each more in- 
significant than the last. Why lose time in thinking 
or dreaming ? We must live at fever heat, must agitate, 
and be infatuated for inanities, must create imaginary 
desires and torments. 

The thoughtful mind, prone to contemplation and 
admiration of the beauties of Nature, is ill at ease in this 
perpetual vortex that swallows everything — satisfaction, 
in a life that one has not time to relish; love of the 
beautiful, that one views with indifference; it is a whirl- 
pool that perpetually hides Truth from us, forgotten 
forever at the bottom of her well. 

And why are our lives thus absorbed in merely 
material interests.? To satisfy our pride and vanity! 
To make ourselves slaves to chimeras! If the Moon 



OUR STAR THE SUN 

were inhabited, and if her denizens could see us plainly 
enough to note and analyze the details of human exist- 
ence on the surface of our planet, it would be curious 
and perhaps a little humiliating for us, to see their 
statistics. What! we should say, is this the sum of our 
lives ? Is it for this that we struggle, and suffer, and 
die ? Truly it is futile to give ourselves such trouble. 

And yet the remedy is simple, within the power of 
every one; but one does not think of it just because it 
is too easy, although it has the immense advantage of 
lifting us out of the miseries of this weary vrorld toward 
the inexpressible happiness that must alwa\s awaken 
in us with the knowledge of the Truth : we need only 
open our eyes to see, and to look out. Only — one 
hardly ever thinks of it, and it is easier to let one's self 
be blinded by the illusion and false glamor of appear- 
ances. 

Think what it would be to consecrate an hour each 
day to voluntary participation in the harmonious Choir 
of Nature, to raise one's eves toward the Heavens, 
to share the lessons taught by the Pageant of the Uni- 
verse! But, no: there is no time, no time for the 
intellectual life, no time to become attached to real 
interests, no time to pursue them. 

Among the objects marshaled for us m the immense 
spectacle of Nature, nothing without exception has 

89 



ASTRONOMY FOR AMATEURS 

struck the admiration and attention of man as much 
as the Sun, the God of Light, the fecundating orb, 
without which our planet and its Hfe would never have 
issued from nonentity, the visible image of the invisible 
god^ as said Cicero, and the poets of antiquity. And 
yet how many beyond the circle of those likely to read 
these pages know that this Sun is a star in the Milky 
Way, and that every star is a sun ? How many take 
any account of the reality and grandeur of the Uni- 
verse ? Inquire, and you will find that the number of 
people who have any notion, however rudimentary, of 
its construction, is singularly restricted. Humanity is 
content to vegetate, much after the fashion of a race of 
moles. 

Henceforward, you will know that you are living 
in the rays of a star, which, from its proximity, we term 
a sun. To the inhabitants of other systems of worlds, our 
splendid Sun is only a more or less brilliant, luminous 
point, according as the spot from which it is observed 
is nearer or farther off. But to us its ''terrestrial" 
importance renders it particularly precious ; we forget 
all the sister stars on its account, and even the most 
ignorant hail it with enthusiasm without exactly knowing 
what its role in the universe may be, simply because they 
feel that they depend on it, and that without it life 
would become extinct on this globe. Yes, it is the 

90 



OUR STAR THE SUN 

beneficent rays of the Sun that shed upon our Earth the 
floods of Hght and heat to which Life owes its existence 
and its perpetual propagation. 

Hail, vast Sun! a little star in Infinitude, but for us 
a colossal and portentous luminary. Hail, divine Bene- 
factor! How should we not adore, when we owe him 
the glow of the warm and cheery days of summer, the 
gentle caresses by which his rays touch the undulating 
ears, and gild them with the touch ? The Sun sustains 
our globe in Space, and keeps it within his rays by the 
mysteriously powerful and delicate cords of attraction. 
It is the Sun that we inhale from the embalmed corollas 
of the flowers that uplift their gracious heads toward 
his light, and reflect his splendors back to us. It is the 
Sun that sparkles in the foam of the merry wine; that 
charms our gaze in those first days of spring, when 
the home of the human race is adorned with all the 
charms of verdant and flowering youth. Everywhere 
we find the Sun; everywhere we recognize his work, 
extending from the infinitely great to the infinitely 
little. We bow to his might, and admire his power. 
When in the sad winter day he disappears behind the 
snowy eaves, we think his fiery globe will never rise to 
mitigate the short December days which are alleviated 
with his languid beams. 

April restores him to superb majesty, and our hearts 

91 



ASTRONOMY FOR AMATEURS 

are filled with hope in the illumination of those beau- 
teous, sunny hours. 



Our celestial journey carried us far indeed from 
our own Solar System. Guided by the penetrating eye 
of the telescope, we reached such distant creations 
that we lost sight of our cherished luminary. 

But we remember that he burns yonder, in the midst 
of the pale cosmic cloud we term the Milky Way. Let 
us approach him, now that we have visited the Isles 
of Light in the Celestial Ocean; let us traverse the vast 
plains strewn with the burning gold of the Suns of the 
Infinite. 

We embark upon a ray of light, and glide rapidly 
to the portals of our Universe. Soon we perceive a 
tiny speck, scintillating feebly in the depths of Space, 
and recognize it as our own celestial quarters. This 
little star shines like the head of a gold pin, and in- 
creases in size as we advance toward it. We traverse 
a few more trillion miles in our rapid course, and it 
shines out like a fine star of the first magnitude. It 
grows larger and larger. Soon we divine that it is 
our humble Earth that is shining before us, and gladly 
alight upon her. In future we shall not quit our own 
province of the Celestial Kingdom, but will enter into 

92 



OUR STAR THE SUN 

relations with this solar family, which interests us the 
more in that it affects us so closely. 




Fig. 28. — Comparative sizes of the Sun and Earth, 

The Sun, which is manifested to us as a fine white 
disk at noon, while it is fiery red in the evening, at its 
setting, is an immense globe, whose colossal dimensions 

93 



ASTRONOMY FOR AMATEURS 

surpass those of our terrestrial atom beyond all con- 
ceivable proportion. 

In diameter, it is, in effect, io8^ times as large as 
the Earth; that is to say, if our planet be represented by 
a globe I meter in diameter, the Sun would figure as a 
sphere io8/^ meters across. This is shown on the ac- 
companying figure (Fig. 28), which is in exact propor- 
tion. 

If our world were set down upon the Sun, with all its 
magnificence, all its wealth, its mountains, its seas, its 
monuments, and its inhabitants, it would only be an im- 
perceptible speck. It would occupy less space in the 
central orb than one grain in a grenade. If the Earth 
were placed in the center of the Sun, with the Moon 
still revolving round it at her proper distance of 384,- 
000 kilometers (238,500 miles), only half the solar sur- 
face would be covered. 

In volume the Sun is 1,280,000 times vaster than 
our abode, and 324,000 times heavier in mass. That 
the giant only appears to us as a small though very 
brilliant disk, is solely on account of its distance. Its 
apparent dimensions by no means reveal its majestic 
proportions to us. 

When observed with astronomical instruments, or 
photographed, we discover that its surface is not smooth, 
as might be supposed, but granulated, presenting a 

94 



OUR STAR THE SUN 

number of luminous points dispersed over a more 
somber background. These granulations are somewhat 
like the pores of a fruit, e. g.^ a fine orange, the color of 
which recalls the hue of the Sun when it sinks in the 
evening, and prepares to plunge us into darkness. At 
times these pores open under the influence of disturb- 
ances that arise upon the solar surface, and give birth 
to a Sun-Spot. For centuries scientists and lay people 
alike refused to admit the existence of these spots, re- 
garding them as so many blemishes upon the King of 
the Heavens. Was not the Sun the emblem of inviolable 
purity t To find any defect in him were to do him 
grievous injury. Since the orb of day was incorruptible, 
those who threw doubt on his immaculate splendor were 
fools and idiots. And so when Scheiner, one of the 
first who studied the solar spots with the telescope, 
published the result of his experiments in i6lo, no one 
^ would believe his statements. 

Yet, from the observations of Galileo and other 
astronomers, it became necessary to accept the evidence, 
and stranger still to recognize that it is by these very 
spots that we are enabled to study the physical consti- 
tution of the Sun. 

They are generally rounded or oval in shape, and 
exhibit two distinct parts; first, the central portion, which 
is black, and is called the nucleus^ or umbra; second, 

95 



ASTRONOMY FOR AMATEURS 

a clearer region, half shaded, which has received the 
name of penumbra. These parts are sharply defined 
in outline; the penumbra is gray, the nucleus looks 
black in relation to the dazzling briUiancy of the solar 




Fig. 29. — Direct photograph of the Sun. 

surface; but as a matter of fact it radiates a light 2,000 
times superior in intensity to that of the full moon. 

Some idea of the aspect of these spots may be ob- 
tained from the accompanying reproduction of a photo- 
graph of the Sun (taken September 8, 1898, at the 

96 



OUR STAR THE SUN 

author's observatory at Juvisy), and from the detailed 
drawing of the large spot that broke out some days 
later (September 13), crossed by a bridge, and furrowed 




tfe^iH. 



Fig. 30. — Telescopic aspect of a Sun-Spot. 

with flames. As a rule, the spots undergo rapid trans- 
formations. 

These spots, which appear of insignificant dimen- 

97 



ASTRONOMY FOR AMATEURS 

sions to the observers on the Earth, are in reality ab- 
solutely gigantic. Some that have been measured 
are ten times as large as the Earth's diameter, /. ^., 
120,000 kilometers (74,500 miles). 

Sometimes the spots are so large that they can be seen 
with the unaided eye (protected with black or dark-blue 
glasses). They are not formed instantaneously, but 
are heralded by a vast commotion on the solar surface, 
exhibiting, as it were, luminous waves or faculce. Out 
of this agitation arises a little spot, that is usually round, 
and enlarges progressively to reach a maximum, after 
which it diminishes, with frequent segmentation and 
shrinkage. Some are visible only for a few days; 
others last for months. Some appear, only to be in- 
stantly swallowed in the boiling turmoil of the flaming 
orb. Sometimes, again, white incandescent w^aves 
emerge, and seem to throw luminous bridges across 
the central umbra. As a rule the spots are not very 
profound. They are funnel-shaped depressions, in- 
ferior in depth to the diameter of the Earth, which, as 
we have seen, is 108 times smaller than that of the Sun, 

The Sun-Spots are not devoid of motion, and from 
their movements we learn that the radiant orb revolves 
upon itself in about twenty-five days. This rotation 
was determined in 161 1, by Galileo, who, while ob- 

98 



OUR STAR THE SUN 

serving the spots, saw that they traversed the solar disk 
from east to w^est, following lines that are oblique to 
the plane of the ecliptic, and that they disappear at the 
western border fourteen days after their arrival at the 
eastern edge. Sometimes the same spot, after being 
invisible for fourteen days, reappears upon the eastern 
edge, where it was observed twenty-eight days pre- 
viously. It progresses toward the center of the Sun, 
which is reached in seven days, disappears anew in 
the west, and continues its journey on the hemisphere 
opposed to us, to reappear under observation two weeks 
later, if it has not meantime been extinguished. This 
observation proves that the Sun revolves upon itself. 
The reappearance of the spots occurs in about twenty- 
seven days, because the Earth is not stationary, and 
in its movement round the burning focus, a motion 
effected in the same direction as the solar rotation, 
the spots are still visible two and a half days after they 
disappeared from the point at which they had been 
twenty-five days previously. In reality, the rotation of 
the Sun occupies twenty-five and a half days, but 
strangely enough this globe does not rotate in one 
uniform period ^ like the Earth; the rotation periods, or 
movements of the different parts of the solar surface, 
diminish from the Sun's equator toward its poles. The 
period is twenty-five days at the equator, twenty-six at 

8 99 

LofC. 



ASTRONOMY FOR AMATEURS 

the twenty-fourth degree of latitude, north or south, 
twenty-seven at the thirty-seventh degree, twenty-eight 
at the forty-eighth. The spots are usually formed 
between the equator and this latitude, more especially 
between the tenth and thirtieth degrees. They have 
never been seen round the poles. 

Toward the edges of the Sun, again, are very bril- 
liant and highly luminous regions, which generally sur- 
round the spots, and have been termed faculcB {facula^ 
3. little torch). These faculae, which frequently occupy 
a very extensive surface, seem to be the seat of formi- 
dable commotions that incessantly revolutionize the face 
of our monarch, often, as we said, preceding the spots. 
They can be detected right up to the poles. 

Our Sun, that appears so calm and majestic, is 
in reality the seat of fierce conflagrations. Volcanic 
eruptions, the most appalling storms, the worst cata- 
clysms that sometimes disturb our little world, are 
gentle zephyrs compared with the solar tempests that 
engender clouds of fire capable at one burst of engulfing 
globes of the dimensions of our planet. 

To compare terrestrial volcanoes with solar erup- 
tions is like comparing the modest night-light that con- 
sumes a midge with the flames of the fire that destroys 
a town. 

The solar spots vary in a fairly regular period of 
lOO 



OUR STAR THE SUN 



eleven to twelve years. In certain years, e. g., 1893, 
they are vast, numerous and frequent; in other years, 
e. g., 1901, they are few and insignificant. The statistics 
are very carefully preserved. Here, for instance, is the 
surface showing sun-spots expressed in millionths of the 
extent of the visible solar surface: 



1889. 
1890. 
1891. 
1892. 
1893. 
1895. 
1896. 



78 


1897 


99 


1898 


569 


1899 


,214 


1900 


,464 


I9OI 


974 


1902 


543 





5H 

375 
III 

75 
29 
62 



The years 1889 and 1901 were minima; the year 1893 
a maximum. 

It is a curious fact that terrestrial magnetism and 
the boreal auroras exhibit an oscillation parallel to 
that of the solar spots, and apparently the same occurs 
with regard to temperature. 

We must regard our sun as a globe of gas in a state 
of combustion, burning at high temperature, and giving 
off a prodigious amount of heat and light. The dazzling 
surface of this globe is called a photosphere (light sphere). 
It is in perpetual motion, like the waves of an ocean 
of fire, whose roseate and transparent flames measure 

lOl 



ASTRONOMY FOR AMATEURS 

some 15,000 kilometers (9,300 miles) in height. This 
stratum of rose-colored flames has received the name of 
chromosphere (color sphere). It is transparent; it is 
not directly visible, but is seen only during the total 
eclipses of the Sun, when the dazzling disk of that 
luminary is entirely concealed by the Moon; or v^ith 
the aid of the spectroscope. The part of the Sun that 
we see is its luminous surface, or photosphere. 

From this agitated surface there is a constant 
ejection of gigantic eruptions, immense jets of flame, 
geysers of fire, projected at a terrific speed to prodig- 
ious heights. 

For years astronomers were greatly perplexed as to 
the nature of these incandescent masses, known as 
prominences, which shot out like fireworks, and were 
only visible during the total eclipses of the Sun. But 
now, thanks to an ingenious invention of Janssen and 
Lockyer, these eruptions can be observed every day 
in the spectroscope, and have been registered since 
1868, more particularly in Rome and in Catania, where 
the Society of Spectroscopists was founded with this 
especial object, and publishes monthly bulletins in 
statistics of the health of the Sun. 

These prominences assume all imaginable forms, and 
often resemble our own storm-clouds; they rise above 
the chromosphere with incredible velocity, often ex- 

102 



OUR STAR THE SUN 

ceeding 200 kilometers (124 miles) per second, and are 
carried up to the amazing height of 300,000 kilometers 
(186,000 miles). 

The Sun is surrounded with these enormous flames 




^#iMMfii 



Fig. 31. — Rose-colored solar flames 228,000 kilometers (141,- 
500 miles) in height, /. e., iS times the diameter of the Earth. 



on every side; sometimes they shoot out into space 
like splendid curving roseate plumes; at others they 
rear their luminous heads in the Heavens, like the 

103 



ASTRONOMY FOR AMATEURS 

cleft and waving leaves of giant palm-trees. Having 
illustrated a remarkable type of solar spot, it is interest- 
ing to submit to the reader a precise observation of 
these curious solar flames. That reproduced here was 
observed in Rome, January 30, 1885, It measured 
228,000 kilometers (141,500 miles) in height, eighteen 
times the diameter of the earth (represented alongside 
in its relative magnitude). (Fig. 31.) 

Solar eruptions have been seen to reach, in a few 
minutes, a height of more than 100,000 kilometers 
(62,000 miles), and then to fall back in a flaming torrent 
into that burning and inextinguishable ocean. 

Observation, in conjunction with spectral analysis, 
shows these prominences to be due to formidable ex- 
plosions produced within the actual substance of the 
Sun, and projecting masses of incandescent hydrogen 
into space with considerable force. 

Nor is this all. During an ecUpse one sees around 
the black disk of the Moon as it passes in front of the 
Sun and intercepts its light, a brilliant and rosy aureole 
with long, luminous, branching feathers streaming out, 
like aigrettes, which extend a very considerable distance 
from the solar surface. This aureole, the nature of 
which is still unknown to us, has received the name of 
corona. It is a sort of immense atmosphere, extremely 
rarefied. Our superb torch, accordingly, is a brazier 

104 



OUR STAR THE SUN 

of unparalleled activity — a globe of gas, agitated by 
phenomenal tempests whose flaming streamers extend 
afar. The smallest of these flames is so potent that it 
would swallow up our world at a single breath, like the 
bombs shot out by Vesuvius, that fall back within the 
crater. 

What now is the real heat of this incandescent focus ? 
The most accurate researches estimate the temperature 
of the surface of the Sun at 7,000° C. The internal 
temperature must be considerably higher. A crucible 
of molten iron poured out upon the Sun would be as a 
stream of ice and snow. 

We can form some idea of this calorific force by 
making certain comparisons. Thus, the heat given out 
appears to be equal to that which would be emitted by 
a colossal globe of the same dimensions (that is, as 
voluminous as twelve hundred and eighty thousand 
terrestrial globes), entirely covered with a layer of in- 
candescent coal 28 kilometers (18 miles) in depth, all 
burning at equal combustion. The heat emitted by 
the Sun, at each second, is equal to that which would 
result from the combustion of eleven quadrillions six 
hundred thousand milliards of tons of coal, all burning 
together. This same heat would bring to the boil in an 
hour, two trillions nine hundred milliards of cubic 
kilometers of water at freezing-point. 

105 



ASTRONOMY FOR AMATEURS 

Our little planet, gravitating at 149,000,000 kilo- 
meters (93,000,000 miles) from the Sun, arrests on the 
way, and utilizes, only the half of a milliard part of this 
total radiation. 

How is this heat maintained ? One of the prin- 
cipal causes of the heat of the Sun is its condensation. 
According to all probabilities, the solar globe repre- 
sents for us the nucleus of a vast nebula, that extended 
in primitive times beyond the orbit of Neptune, and 
which in its contraction has finally produced this central 
focus. In virtue of the law of transformation of motion 
into heat, this condensation, which has not yet reached 
its limit, suffices to raise this colossal globe to its level 
of temperature, and to maintain it there for millions of 
years. In addition, a substantial number of meteors 
is forever falling into it. This furnace is a true pande- 
monium. 

The Sun weighs three hundred and twenty-four 
thousand times more than the Earth — that is to say, 
eighteen hundred and seventy octillions of kilograms: 

1,870,000,000,000,000,000,000,000,000,000 
(1,842,364,532,019,704,433,497,536,945 tons). 

In Chapter XI we shall explain the methods by which 
it has been found possible to weigh the Sun and deter- 
mine its exact distance. 



106 



OUR STAR THE SUN 

I trust these figures will convey some notion of the 
importance and nature of the Sun, the stupendous orb 
on whose rays our very existence depends. Its apparent 
dimension (which is only half a degree, 32^ and would 
be hidden from sight, like that of the full moon, which 
is about the same, by the tip of the Httle finger held 
out at arm's length), represents, as we have seen, a real 
dimension that is colossal, /. ^., 1,383,000 kilometers 
(more than 857,000 miles), and this is owing to the 
enormous distance that separates us from it. This 
distance of 149,000,000 kilometers (93,000,000 miles) 
is sufficiently hard to appreciate. Let us say that 
11,640 terrestrial globes would be required to throw a 
bridge from here to the Sun, while 30 would suffice from 
the Earth to the Moon. The Moon is 388 times nearer 
to us than the Sun. We may perhaps conceive of this 
distance by calculating that a train, moving at constant 
speed of i kilometer (0.6214 mile) a minute, would take 
149,000,000 minutes, that is to say 103,472 days, or 
283 years, to cross the distance that separates us from 
this orb. Given the normal duration of life, neither 
the travelers who set out for the Sun, nor their children, 
nor their grandchildren, would arrive there: only the 
seventh generation would reach the goal, and only the 
fourteenth could bring us back news of it. 

Children often cry for the Moon. If one of these 
107 



ASTRONOMY FOR AMATEURS 

inquisitive little beings could stretch out its arms to 
touch the Sun, and burn its fingers there, it would not 
feel the burn for one hundred and sixty-seven years 
(when it would no longer be an infant), for the nervous 
impulse of sensation can only be transmitted from the 
ends of the fingers to the brain at a velocity of 28 meters 
per second. 

'Tis long. A cannon-ball would reach the Sun in 
ten years. Light, that rapid arrow that flies through 
space at a velocity of 300,000 kilometers (186,000 miles 
per second), takes only eight minutes seventeen seconds 
to traverse this distance. 

This brilliant Sun is not only sovereign of the 
Earth; he is also the head of a vast planetary system. 

The orbs that circle round the Sun are opaque bodies, 
spherical in shape, receiving their light and heat from 
the central star, on which they absolutely depend. The 
name of planets given to them signifies ^'wandering" 
stars. If you observe the Heavens on a fine starry night, 
and are sufficiently acquainted with the principal stars 
of the Zodiac as described in a preceding chapter, you 
may be surprised on certain evenings to see the figure 
of some zodiacal constellation slightly modified by the 
temporary presence of a brilliant orb perhaps surpassing 
in its luminosity the finest stars of the first magnitude. 

108 



OUR STAR THE SUN 

If you watch this apparition for some weeks, and 
examine its position carefully in regard to the adjacent 
stars, you will observe that it changes its position more 
or less slowly in the Heavens. These wandering orbs, 
or planets, do not shine with intrinsic light; they are 
illuminated by the Sun. 

The planets, in effect, are bodies as opaque as the 
Earth, traveling round the God of Day at a speed pro- 
portional to their distance. They nurn^er eight prin- 
cipal orbs, and may be divided into two quite distinct 
groups by which we may recognize them: the first com- 
prises four planets, of relatively small dimensions in 
comparison with those of the second group, which are 
so voluminous that the least important of them is larger 
than the other four put together. 

In order of distance from the Sun, we first encounter: 

MERCURY, VENUS, THE EARTH, AND MARS 

These are the w^orlds that are nearest to the orb of 
day. 

The four following, and much more remote, are, 
still in order of distance: 

JUPITER, SATURN, URANUS, AND NEPTUNE 

This second group is separated from the first by a 
vast space occupied by quite a little army of minute 
planets, tiny cosmic bodies, the largest of which meas- 

109 



ASTRONOMY FOR AMATEURS 

ures little more than loo kilometers (62 miles) in di- 
ameter, and the smallest some few miles only. 

The planets which form these three groups represent 
the principal members of the solar family. But the Sun 
is a patriarch, and each of his daughters has her own 
children who, while obeying the paternal influence of 
the fiery orb, are also obedient to the world that governs 
them. These secondary asters, or satellites, follow the 
planets in their course, and revolve round them in an 
ellipse, just as the others rotate round the Sun. Every 
one knows the satellite of the Earth, the Moon. All 
the other planets of our system have their own moons, 
some being even more favored than ourselves in this 
respect, and having several. Mars has two; Jupiter, 
five; Saturn, eight; Uranus, four; and Neptune, one 
(at least as yet discovered). 

In order to realize the relations between these worlds, 
we must appreciate their distances by arranging them 
in a little table: 

Distance in Distance in 
Millions of Millions of 

Kilometers. Miles. 

Mercury 57 35 

Venus 108 67 

The Earth 149 93 

Mars 226 140 

Jupiter 775 4^^ 

Saturn 1,421 882 

Uranus. 2,831 1,755 

Neptune 4>470 2,771 

I 10 



OUR STAR THE SUN 

The Sun is at the center (or, more properly speaking, 
at the focus, for the planets describe an ellipse) of this 
system, and controls them. Neptune is thirty times 
farther from the Sun than the Earth. These disparities 
of distance produce a vast difference in the periods of 
the planetary revolutions; for v^hile the Earth revolves 
round the Sun in a year, Venus in 224 days, and Mercury 
in 88, Mars takes nearly 2 years to accomplish his 
journey, Jupiter 12 years, Saturn 29, Uranus 84, and 
Neptune 165. 

Even the planets and their moons do not represent 
the Sun's complete paternity. There are further, in 
the solar republic, certain vagabond and irregular orbs 
that travel at a speed that is often most immoderate, 
occasionally approaching the Sun, not to be consumed 
therein, but, as it appears, to draw^ from its radiant 
source the provision of forces necessary for their peri- 
grinations through space. These are the Comets, which 
pursue an extremely elongated orbit round the Sun, to 
which at times they approximate very closely, at other 
rimes being excessively distant. 

And now to recapitulate our knowledge of the Solar 
Empire. In the first place, we see a colossal globe of fire 
dominating and governing the worlds that belong to 
him. Around him are grouped planets, in number eight 
principal, formed of solid and obscure matter, gravi- 

III 



ASTRONOMY FOR AMATEURS 

tating round the central orb. Other secondary orbs, the 
satelHtes, revolve round the planets, which keep them 
w^ithin the sphere of their attraction. And lastly, the 
comets, irregular celestial bodies, track the v^hole 
extent of the great solar province. To these might be 
added the whirlv^inds of meteors, as it were disaggre- 
gated comets, which also circle round the Sun, and give 
origin to shooting stars, when they come into collision 
with the Earth. 

Having now a general idea of our celestial family, and 
an appreciation of the potent focus that controls it, let 
us make direct acquaintance with the several members 
of which it is composed. 



112 



CHAPTER V 

THE PLANETS 

j4, — Mercury, Venus, the Earth, Mars 

And now we are in the Solar System, at the center, 
or, better, at the focus of which burns the immense and 
dazzHng orb. We have appreciated the grandeur and 
potency of the solar globe, whose rays spread out in active 
waves that bear a fecundating illumination to the worlds 
that gravitate round him; we have appreciated the dis- 
tance that separates the Sun from the Earth, the third 
of the planets retained within his domain, or at least I 
trust that the comparisons of the times required by 
certain moving objects to traverse this distance have 
enabled us to conceive it. 

We said that the four planets nearest to the Sun are 
Mercury, at a distance of 57 million kilometers (35,000,- 
000 miles); Venus, at 108 million (67,000,000 miles); 
the Earth, at 149 million (93,000,000 miles); and Mars 
at 226 million (140,000,000 miles). Let us begin our 
planetary journey with these four stations. 

113 



ASTRONOMY FOR AMATEURS 



MERCURY 

A little above the Sun one sometimes sees, now in 
the West, in the lingering shimmer of the twilight, now 
in the East, when the tender roseate dawn announces 
the advent of a clear day, a small star of the first mag- 
nitude which remains but a very short time above the 
horizon, and then plunges back into the flaming sun. 
This is Mercury, the agile and active messenger of 
Olympus, the god of eloquence, of medicine, of com- 
merce, and of thieves. One only sees him furtively, 
from time to time, at the periods of his greatest elonga- 
tions, either after the setting or before the rising of the 
radiant orb, when he presents the aspect of a somewhat 
reddish star. 

This planet, like the others, shines only by the re- 
flection of the Sun whose illumination he receives, and 
as he is in close juxtaposition with it, his light is bright 
enough, though his volume is inconsiderable. He is 
smaller than the Earth. His revolution round the Sun 
being accomplished in about three months, he passes 
rapidly, in a month and a half, from one side to the 
other of the orb of day, and is alternately a morning 
and an evening star. The ancients originally regarded 
it as two separate planets; but with attentive obser- 

114 



THE PLANETS 

vation, they soon perceived its identity. In our some- 
what foggy cHmates, it can only be discovered once or 
twice a year, and then only by looking for it according 
to the indications given in the astronomic almanacs. 




Co; days 

Fig. 32. — Orbits of the four Planets nearest to the Sun. 



Mercury courses round the Sun at a distance of 
57,000,000 kilometers (35,000,000 miles), and accom- 
plishes his revolution in 87 days, 23 hours, 15 minutes; 
t. e., 2 months, 27 days, 23 hours, or a little less than 
three of our months. If the conditions of life are the 
9 115 



ASTRONOMY FOR AMATEURS 



same there as here, the existence of the Mercurians 
must be four times as short as our own. A youth of 
twenty, awaking to the promise of the Hfe he is just 
beginning in this world, is an octogenarian in Mercury. 



xjcars 



/Neptune 





Uranus 



Saturn 







Fig. 33.^ — Orbits of the four Planets farthest from the Sun. 



There the fair sex would indeed be justified in bewailing 
the transitory nature of life, and might regret the years 
that pass too quickly away. Perhaps, however, they are 
more philosophic than with us. 

116 



THE PLANETS 



The orbit of Mercury, which of course is within that 
of the Earth, is not circular, but elHptical, and very 
eccentric, so elongated that at certain times of the year 
this planet is extremely remote from the solar focus, and 
receives only half as much heat and light as at the op- 
posite period; and, in consequence, his distance from the 
Earth varies con- 
siderably. 

This globe 
exhibits phases^ 
discovered in the 
seventeenth cen- 
tury by Galileo, 
which recall 
those of the 
Moon. They are 
due to the mo- 
tions of the 
planet round the 
Sun, and are invisible to the unaided eye, but with even 
a small instrument, one can follow the gradations and 
study Mercury under every aspect. Sometimes, again^ 
he passes exactly in front of the Sun, and his disk is 
projected like a black point upon the luminous surface 
of the flaming orb. This occurred, notably, on May lo, 
1891, and November 10, 1894; and the phenomenon 

117 




Fig. 34. — Mercury near quadrature. 



ASTRONOMY FOR AMATEURS 

will recur on November 12, 1907, and November 6, 

1914. 

Mercury is the least of all the v^orlds in our system 
(v^ith the exception of the cosmic fragments that circulate 
between the orbit of Mars and that of Jupiter). His 
volume equals only j^-q that of the Earth. His diameter, 
in comparison w^ith that of our planet, is in the ratio of 
373 to 1,000 (a little more than /^) and measures 4,750 
kilometers (2,946 miles). His density is the highest of 
all the w^orlds in the great solar family, and exceeds that 
of our Earth by about ys; but weight there is less by 
almost y4. 

Mercury is enveloped in a very dense, thick atmos- 
phere, which doubtless sensibly tempers the solar heat, 
for the Sun exhibits to the Mercurians a luminous disk 
about seven times more extensive than that with which 
we are familiar on the Earth, and when Mercury is at 
perihelion (that is, nearest to the Sun), his inhabitants 
receive ten times more light and heat than we obtain at 
midsummer. In all probability, it would be impossible 
for us to set foot on this planet without being shattered 
by a sunstroke. 

Yet we may well imagine that Nature's fecundity can 
have engendered beings there of an organization different 
from our own, adapted to an existence in the proximity 
of fire. What magnificent landscapes may there be 

118 



THE PLANETS 

adorned with the luxuriant vegetation that develops 
rapidly under an ardent and generous sun ? 



Fig. 35. — The Earth viewed from Mercury. 
Observations of Mercury are taken under great 
difficulties, just because of the immediate proximity of 

119 



ASTRONOMY FOR AMATEURS 

the solar furnace; yet some have detected patches that 
might be seas. In any case, these observations are con- 
tradictory and uncertain. 

Up to the present it has been impossible to determine 
the duration of the rotation. Some astronomers even 
think that the Sun's close proximity must have produced 
strong tides, that would, as it w^ere, have immobilized 
the globe of Mercury, just as the Earth has immobilized 
the Moon, forcing it perpetually to present the same 
side to the Sun. From the point of view of habitation, 
this situation would be somewhat peculiar; perpetual 
day upon the illumined half, perpetual night upon the 
other hemisphere, and a fairly large zone of twilight be- 
tween the two. Such a condition would indeed be differ- 
ent from the succession of terrestrial days and nights. 

As seen from Mercury, the Earth we inhabit would 
shine out in the starry sky * as a magnificent orb of first 

* The author has endeavored on the plates to represent the aspect of the 
Earth in the starry sky of Mercury, Venus, and Marsj but in all representa- 
tions of this kind the stars are necessarily made too large. By calculation 
the diameters of the Earth and Moon as seen from the planets, and their 

distances, are as follows: 

Diameter of Diameter of Distance 

the Earth. the Moon. Earth-JNIoon. 

Of Mercury (opposition) 20'' 8'' 871'' 

Of Venus (opposition) 64'' y-]" 1,928'' 

Of Mars (quadrature) 15'' 4'' 464'' 

Of Jupiter (quadrature) 3 ''5 o" \ 105'' 

These aspects will be appreciated if we rememoer that the distance of the 

components of e Lyre r= 207^', that of Atlas in Pleione -.^ 301', and that of 

the stars Mizar and Alcor = 70 8 '^ 

120 



THE PLANETS 

magnitude, with the Moon alongside, a faithful little 
companion. They should form a fine double star, the 
Earth being a brilliant orb of first magnitude, and the 
Moon of third, a charming couple, and admired doubtless 
as an enchanted and privileged abode. 

It is at midnight during the oppositions of the Earth 
with the Sun that our planet is the most beautiful and 
brilliant, as is Jupiter for ourselves. The constellations 
are the same, viewed from Mercury or from, the Earth. 

But is this little solar planet inhabited ^ We do not 
yet know. We can only reply: why not ^ 



VENUS 

When the sunset atmosphere is crimson with the 
glorious rays of the King of Orbs, and all Nature as- 
sumes the brooding veil of twilight, the most indifferent 
eyes are often attracted and captivated by the presence 
of a star that is almost dazzling, and illuminates with 
its white and limpid light the heavens darkened by the 
disappearance of the God of Day. 

Hail, Venus, Queen of the Heavens! the " Shepherd's 
Star," gentle mother of the loves, goddess of beauty, eter- 
nally adored and cherished, sung and immortalized upon 
Earth, by poets and artists. Her splendid brilliancy 
attracted notice from earliest antiquity, and we find her, 

121 



ASTRONOMY FOR AMATEURS 

radiant and charming, in the works of the ancients, who 
erected altars to her and adorned their poetry with her 
grace and beauty. Homer calls her Callisto the Beau- 
tiful; Cicero names her Vesper, the evening star, and 
Lucifer, the star of the morning — for it was with this 
divinity as with Mercury. For a long while she was 
regarded as two separate planets, and it was only when 
it came to be observed that the evening and the morning 
star were always in periodic succession, that the identity 
of the orb was recognized. 

Her radiant splendor created her mythological per- 
sonality, just as the agility of Mercury created that of 
the messenger of the gods. 

We do not see her aerial chariot in the Heavens drawn 
by a flight of doves with white and fluttering wings, but 
we follow the lustrous orb led on through space by solar 
attraction. And in the beautiful evenings when she is 
at her greatest distance from our Sun, the whole world 
admires this white and dazzling Venus reigning as sov- 
ereign over our twilight * for hours after sunset, and in 
addition to the savants who are practically occupied 

* A few evenings ago, after observing Venus in the calm and silent Heavens 
at the close of day, my eyes fell upon a drawing sent me by my friend Gustave 
Dore, which is included in the illustrations of his wonderful edition of Dante's 
Divina Commedia. This drawing seems to be in place here, and 1 offer my 
readers a poor reproduction of it, taken from the fine engraving in the book. 
Dante and Virgil, in the peaceful evening, are contemplating lo bel planeta 
ch'ad amar conforta (the beautiful pbnet that mcites to love) 

122 



THE PLANETS 

with astronomy, millions of eyes are raised to this celes- 
tial splendor, and for a moment millions of human beings 




Fig. 36. — The Evening Star. 

feel some curiosity about the mysteries of the Infinite. 
The brutalities of daily life would fain petrify our dreams, 
but thought is not yet stifled to the point of checking all 

123 



ASTRONOMY FOR AMATEURS 

aspirations after eternal truth, and when we gaze at the 
starry sky it is hard not to ask ourselves the nature of 
those other worlds, and the place occupied by our own 
planet in the vast concert of sidereal harmony. 

Even through a small telescope, Venus offers re- 
markable phases. 

Fig. 37 gives some notion of the succession of these, 
and of the planet's variations in magnitude during its 




Fig. 37. — Successive phases of Venus. 



journey round the Sun. Imagine it to be rotating in a 
year of 224 days, 16 hours, 49 minutes, 8 seconds at a 
distance of 108 million kilometers (67,000,000 miles), 
the Earth being at 149 million (93,000,000 miles). Like 
Mercury, at certain periods it passes between the Sun 
and ourselves, and as its illuminated hemisphere is of 
course turned toward the orb of day, we at those times 
perceive only a sharp and very luminous crescent. At 

124 



THE PLANETS 

such periods Venus is entirely, so to say, against the Sun, 
and presents to us her greatest apparent dimension 
(Fig. 38). Sometimes, again, Hke Mercury, she passes 
immediately in front of the Sun, forming a perfectly 
round black spot; this happened on December 8, 1874, 
and December 6, 1882; and will recur on June 7, 2004, 
and June 5, 2012^ These transits have been utilized in 
celestial geometry in measuring the distance of the Sun. 

You will readily divine that the distance of Venus 
varies considerably according to her position in relation 
to the Earth: when she is between the Sun and ourselves 
she is nearest to our world; but it is just at those times 
that we see least of her surface, because she exhibits to 
us only a slender crescent. Terrestrial astronomers are 
accordingly very badly placed for the study of her phys- 
ical constitution. The best observations can be made 
when she is situated to right or left of the Sun, and shows 
us about half her illuminated disk — during the day for 
choice, because at night there is too much irradiation 
from her dazzling light. 

These phases were discovered by Galileo, in 16 10. 
His observations were among the first that confirmed 
the veracity of the system of Copernicus, affording an 
evident example of the movement of the planets round 
the sun. They are often visible to the unaided eye with 
good sight, either at dusk, or through light clouds. 

125 



ASTRONOMY FOR AMATEURS 



Venus, surrounded by a highly dense and rarefied 
atmosphere, which increases the difficulties of observ- 
ing her surface, might be called the twin sister of the 
Earth, so similar are the dimensions of the two worlds. 
But, strange as it may seem to the many admirers, who 
are ready to hail in her an abode of joy and happiness, 

It is most prob- 
able that this 
planet, attract- 
ive as she is at a 
distance, would 
be a less desir- 
able habitation 
than our float- 
ing island. In 
fact, the atmos- 
I phere of Venus 
is perpetually 
covered with 




Fig. 38. — Venus at greatest brilliancy. 



cloud, so that the weather there must be always foggy. 
No definite geographical configuration can be discovered 
on her, despite the hopes of the eighteenth-century astron- 
omers. We are not even sure that she rotates upon her- 
self, so contradictory are the observations, and so hard 
is it to distinguish anything clearly upon her surface. A 
single night of observation suffices to show the rotation 

126 



THE PLANETS 

of Mars or of Jupiter; but the beautiful Evening Star 
remains obstinately veiled from our curiosity. 

Several astronomers, and not the least considerable, 
think that the tides produced by the Sun upon her seas, 
or globe in its state of pristine fluidity, must have been 
strong enough to seize and fix her, as the Earth did for 
the Moon, thus obliging her to present always the same 
face to the Sun. Certain telescopic observations w^ould 
even seem to confirm this theoretical deduction from the 
calculations of celestial mechanics. 

The author ventures to disagree v^ith this opinion, 
its apparent probability notv^ithstanding, because he has 
invariably received a contrary impression from all his 
telescopic observations. He has quite recently (spring 
of 1903) repeated these observations. Choosing a re- 
markably clear and perfectly calm atmosphere, he 
examined the splendid planet several times v^ith great 
attention in the field of the telescope. The right or 
eastern border (reversed image) was dulled by the at- 
mosphere of Venus; this is the line of separation between 
day and night. Beneath, at the extreme northern edge, 
he was attracted on each occasion by a small white 
patch, a little whiter than the rest of the surface of the 
planet, surrounded by a light-gray penumbra, giving the 
exact effect of a polar snow, very analogous to that 
observed at the poles of Mars. To the author this white 

127 



ASTRONOMY FOR AMATEURS 

spot on the boreal horn of Venus does not appear to 
be due to an effect of contrast, as has sometimes been 
supposed. 

Now, if the globe of Venus has poles, it must turn 
upon itself. 

Unfortunately it has proved impossible to distinguish 
any sign upon the disk, indicative of the direction and 
speed of its rotary movement, although these observa- 
tions v^ere made, v^ith others, under excellent conditions. 
— Three o'clock in the afternoon, brilliant sun, sky 
clear blue, the planet but little removed from the 
meridian — at which time it is less dazzling than in the 
evening. 

There is merely the impression; but it is so definite 
as to prevent the author from adopting the new hypoth- 
esis, in virtue of which the planet, as it gravitates 
round the Sun, presents always the same hemisphere. 

If this hypothesis were a reality, Venus would cer- 
tainly be a very peculiar world. Eternal day on the one 
side; eternal night on the other. Maximum light and 
heat at the center of the hemisphere perpetually turned 
to the Sun; maximum cold and center of night at the 
antipodes. This icy hemisphere would possibly be 
uninhabitable, but the resources of Nature are so pro- 
digious, and the law of Life is so imperious, so persist- 
ent, under the most disadvantageous and deplorable 

128 



THE PLANETS 

terrestrial conditions, that it would be transcending our 
rights to declare an impossibility of existence, even in 
this eternal night. The currents of the atmosphere 
would no doubt suffice to set up perpetual changes of 
temperature between the two hemispheres, in compari- 
son with which our trade-winds would be the lightest of 
breezes. 

Yes, mystery still reigns upon this adjacent earth, 
and the most powerful instruments of the observatories 
of the whole world have been unable to solve it. All 
we know is that the diameter, surface, volume and mass 
of this planet, and its weight at the surface, do not differ 
sensibly from those that characterize our own globe : 
that this planet is sister to our own, and of the same 
order, hence probably formed of the same elements. 
We further know that, as seen from Venus (Fig. 39), the 
Earth on which we live is a magnificent star, a double 
orb more brilliant even than when viewed from Mer- 
cury. It is a dazzling orb of first magnitude, accom- 
panied by its moon, a star of the second and a half 
magnitude. 

And thus the worlds float on in space, distant sym- 
bols of hopes not realized on any one of them, all at 
different stages of their degree of evolution, repre- 
senting an ever-growing progress in the sequence of 
the ages. 

129 



ASTRONOMY FOR AMATEURS 




Fig. 39. — The Earth viewed from Venus. 

When we contemplate this radiant Venus, it is diffi- 
cult, even if v^e can not form any definite idea as to her 
actual state as regards habitation, to assume that she 

130 



THE PLANETS 

must be a dreary desert, and not, on the contrary, to hail 
in her a celestial land, differing more or less from our 
own dwelling-place, travailing with her sisters in the 
accomplishment of the general plan of Nature. 

Such are the characteristic features of our celestial 
neighbor. In quitting her, we reach the Earth, which 
comes immediately next her in order of distance, 149 
million kilometers (93,000,000 miles) from the Sun, but 
as we shall devote an entire chapter to our own planet, 
we will not halt at this point, but cross in one step the 
distance that separates Mars from Venus. 

Let us only remark in passing, that our planet is the 
largest of the four spheres adjacent to the Sun. Here 
are their comparative diameters: 

The Earth = i. In Kilometers. In Miles. 

Mercury 0-373 4>75o 2j946 

Venus 0.999 i^>73o 7*894 

Earth 1 . 000 1 2, 742 7)9^6 

Mars o. 528 6,728 45I72 

It will be seen that Venus is almost identical with 
the Earth. 

MARS 

Two hundred and twenty-six millions of kilometers 
(140,000,000 miles) from the Sun is the planet Mars, 
gravitating in an orbit exterior to that which the Earth 
takes annually round the same center. 

10 131 



ASTRONOMY FOR AMATEURS 

Unfortunate Mars! What evil fairy presided at his 
birth ? From antiquity, all curses seem to have fallen 
upon him. He is the god of war and of carnage, the 
protector of armies, the inspirer of hatred among the 
peoples, it is he who pours out the blood of Humanity in 
international hecatombs. Here, again, as in the case of 
Mercury and Venus, the appearance has originated the 
idea. Mars, in fact, burns like a drop of blood in the 
depths of the firmament, and it is this ruddy color that 
inspired its name and attributes, just as the dazzling 
whiteness of Venus made her the goddess of love and 
beauty. Why, indeed, should the origins of mythology 
be sought elsewhere than in astronomy ? 

While Humanity was attributing to the presumptive 
influence of Mars the defects inherent in its own terres- 
trial nature, this world, unwitting of our sorrows, pur- 
sued the celestial path marked out for it in space by 
destiny. 

This planet is, as we have said, the first encountered 
after the Earth. Its orbit is very elongated, very eccen- 
tric. Mars accomplishes it in a period of i year, 321 
days, 22 hours, /. ^., i year, 10 months, 21 days, or 
687 days. The velocity of its transit is 23 kilometers 
(14.5 miles) per second; that of the Earth is 30 (19 miles). 
Our planet, traveling through space at an average dis- 
tance of 149 million kilometers (93,000,000 miles) from 

132 



THE PLANETS 

the central focus, is separated from Mars by an average 
distance of 76 million kilometers (47,000,000 miles); but 
as its orbit is equally elliptic and elongated it follows 
that at certain epochs the two planets approach one 
another by something less than 60 million kilometers 
(37,000,000 miles). These are the periods selected for 
making the best observations upon our neighbor of the 
ruddy rays. The oppositions of Mars arrive about 
every twenty-six months, but the periods of its greatest 
proximity, when this planet approaches to within 
56 million kilometers (34,700,000 miles) of the Earth, 
occur only every fifteen years. 

Mars is then passing perihelion, while our world is 
at aphelion (or greatest distance from the Sun). At 
such epochs this globe presents to us an apparent 
diameter 63 times smaller than that of the Moon, /. <?., a 
telescope that magnifies 63 times would show him to us 
of the same magnitude as our satellite viewed with the 
unaided eye, and an instrument that magnified 630 times 
would show him ten times larger in diameter. 

In dimensions he differs considerably from our world, 
being almost half the size of the Earth. In diameter 
he measures only 6,728 kilometers (4,172 miles), and 
his circumference is 21,125 kilometers (13,000 miles). 
His surface is only j^-q^q- of the terrestrial surface, and 
his volume only -^-^-q of our own. 

133 



ASTRONOMY FOR AMATEURS 

This difference in volume causes Mars to be an 
earth in miniature. When we study his aspects, his 
geography, his meteorology, we seem to see in space a 
reduction of our own abode, with certain dissimilarities 
that excite our curiosity, and make him even more inter- 
esting to us. 

The Martian world weighs nine times and a half 
less than our own. If we represent the weight of the 
Earth by i,ooo, that of Mars would be represented by 
105. His density is much less than our own; it is only 
Y^Q- that of the Earth. A man weighing 70 kilograms, 
transported to the adjacent globe, would weigh only 
26 kilograms. 

The earliest telescopic observations revealed the 
existence of more or less accentuated markings upon 
the surface of Mars. The progress of optics, admitting 
of greater magnifications, exhibited the form of these 
patches more clearly, while the study of their motions 
enabled the astronomers to determine with remarkable 
precision the diurnal rotation of this planet. It occurs 
in 24 hours, 37 minutes, 23.65 seconds. Day and night 
are accordingly a little longer on Mars than on the 
Earth, but the difference is obviously inconsiderable. 
The year of Mars consists of 668 Martian days. The 
inclination of the axis of rotation of this globe upon 
the plane of its orbit is much the same as our own. In 



THE PLANETS 

consequence, its seasons are analogous to ours in in- 
tensity, while twice the length, the Martian year be- 
ing almost equal to two of our years. The intensity of 
the seasons is indeed more accentuated than upon the 
Earth, since the orbit of Mars is very elongated. But 
there, as here, are three quite distinct zones: the torrid, 
the temperate, and the glacial. 

By means of the telescope we can follow the varia- 
tions of the Martian seasons, especially in what concerns 
the polar snows, which regularly aggregate during the 
winter, and melt no less regularly during the heat of the 
summer. These snows are very easily observed, and 
stand out clearly with dazzling whiteness. The reader 
can judge of them by the accompanying figure, which 
sums up the author's observations during one of the 
recent oppositions of Mars (1900-1901). The size of 
the polar cap diminished from 4,680 kilometers to 840. 
The solstice of the Martian summer was on April nth. 
The snows were still melting on July 6th. Sometimes 
they disappear almost entirely during the Martian 
month that corresponds to our month of August, as 
never happens with our polar ice. Hence, though this 
planet is farther away from the Sun than ourselves, it 
does not appear to be colder, or, at any rate, it is certain 
that the polar snows are much less thick. 

On the other hand, there are hardly ever clouds on 




ASTRONOMY FOR AMATEURS 

^31 Mars; the Martian atmosphere is al- 
most always limpid, and one can say 



October 23, 1900. 



'^E^i^&i^ 



December 22, 1900. 




that fine weather is the chronic state 
of the planet. At times, light fogs or 
a little vapor will appear in certain 
regions, but they are soon dissipated, 
and the sky clears up again. 

Since the invention of the teles- 
cope, a considerable number of draw- 
ings have been made, depicting Mars 
under every aspect, and the agree- 
ment between these numerous obser- 
vations gives us a sufficient acquaint- 
ance with the planet to admit of our 
indicating the characteristic features 
of its geography, and of drawing out 
areographic maps (Ares, Mars). Its 
appearance can be judged of from 
the two drawings here reproduced, as 
made (February, 1901) at the Observ- 
atory of Juvisy, and from the general 
chart drawn from the total sum of 
observations (Figs. 41, 42 and 43). 

It will be seen at the first glance 

snows of Mars ^^^^ ^^le geography of Mars is very 

during thesum-. 

different from that of our own globe: 
mer. o 

136 



February i 


T, luOl. 


^■^^2^ 


m 


IMarch 22 


. 1901. 


Bm 


April 21, 


1901. 


^^H 


May 19, 


1901. 


HH 


June 14, 


1901. 


HH 



Jul}' 6, 1 901. 

Fig. 40. — Dimi- 
nution of the polar 



THE PLANETS 

while three-quarters of the Earth are covered with the 
Hquid element, Mars seems to be more evenly divided, 
and must indeed have rather more land than water. 
We find no immense oceans surrounding the continents, 
and separating them like islands; on the contrary, the 
seas are reduced to long gulfs compressed between the 
shores, like the 
Mediterranean 
for example, nor 
is it even certain 
that these gray 
spots do all rep- 
resent true seas. 
It has been 
agreed to term 
sea the parts that 
are lightly tinged 

with green, and 

Fig. 41. — Telescopic aspect of the planet 
to give the name , , ,^ , . 

^ Mars (Feb., 1901). 

o f continent t o 

the spots colored yellow. That is the hue of the Mar- 
tian soil, due either to the soil itself, which would re- 
semble that of the Sahara, or, to take a less arid region, 
that seen on the line between Marseilles and Nice, in 
the vicinity of the Esterels; or perhaps to some peculiar 
vegetation. During ascents in a balloon, the author 




ASTRONOMY FOR AMATEURS 



has often remarked that the hue of the ripe corn, with 
the Sun shining on it, is precisely that presented to us 
by the continents of Mars in the best hours for obser- 
vation. 

As to the *'seas/* it is pretty certain that there must 
be water, or some kind of Hquid, deriving above all 

from the melting 
of the polar 
snows in spring 
and summer; but 
it may possibly 
be in conjunction 
with some vege- 
tation, aquatic 
plants, or per- 
haps vast mea- 
dows, which ap- 
pear to us from 
here to be the 
more consider- 
able in proportion as the water that nourishes them 
has been more abundant. 

Mars, like our globe, is surrounded with a protective 
atmosphere, which retains the rays of the Sun, and must 
preserve a medium temperature favorable to the con- 
servation of life upon the surface of the planet. But the 

138 




Fig. 42. — Telescopic aspect of the planet 
Mars (Feb., 1901). 



THE PLANETS 

circulation of the water, so important to terrestrial life, 
whether animal or vegetable, which is effected upon our 
planet by the evaporation of the seas, clouds, winds, 
rains, wells, rivers and streams, comes about quite dif- 
ferently on Mars; for, as was remarked above, it is rarely 
that any clouds are observed there. Instead of being 
Vertical, as here, this circulation is horizontal: the 
water coming from the source of the polar snows finds 
its way into the canals and seas, and returns to be con- 
densed at the poles by a light drift of invisible vapors 
directed from the equator to the poles. There is never 
any rain. 

We have spoken o{ canals. One of the great puzzles 
of the Martian world is incontestably the appearance 
of straight lines that furrow its surface in all directions, 
and seem to connect the seas. M. Schiaparelli, the 
distinguished Director of the Observatory of Milan, 
who discovered them in 1877, called them canals, with- 
out, however, postulating anything as to their real 
nature. Are they indeed canals ? These straight lines, 
measuring sometimes 600 kilometers (372 miles) in 
length, and more than 100 kilometers (62 miles) in 
breadth, have much the same hue as the seas on which 
they open. For a quarter of a century they have been 
surveyed by the greater number of our observers. But 
it must be confessed that, even with the best instruments, 

139 




o o 



QC^Mi'^K 






>|o- 



= ^ 



u 



t 

t 



i 









2 o 
&3 



140 



THE PLANETS 

we only approach Mars at a distance of 60,000 kilometers 
(37,200 miles), which is still a little far off, and we may 
be sure that we do not distinguish the true details of 
the surface."^ These details at the limits of visibility 
produce the appearance of canals to our eyes. They 
may possibly be lines of lakes, or oases. The future 
will no doubt clear up this mystery for us. 

As to the inhabitants of Mars, this world is in a 
situation as favorable as our Earth for habitation, and 
it would be difficult to discover any reason for perpetual 
sterility there. It appears to us, on the contrary^, by its 
rapid and frequent variations of aspect, to be a very 
living world. Its atmosphere, which is always clear, has 
not the density of our own, and resembles that of the 
highest mountains. The conditions of existence there 
vary from ours, and appear to be more delicate, more 
ethereal. 

There as here, day succeeds to night, spring softens 
the rigors of winter; the seasons unfold, less disparate 
than our own, of which we have such frequent reason 
to complain. The sky is perpetually clear. There are 
never tempests, hurricanes, nor cyclones, the wind never 
gets up any force there, on account of the rarity of the 
atmosphere, and the low intensity of weight. 

■^ Strictly speaking, i kilometer = 0.6214 mile. Here, as throughout, 
the equivalents are only given in round numbers. — Translator. 

141 



ASTRONOMY FOR AMATEURS 

Differing from ours, this world may well be a more 
congenial habitation. It is more ancient than the 
Earth, smaller, less massive. It has run more quickly 
through the phases of its evolution. Its astral life is 
more advanced, and its Humanity should be superior 
to our own, just as our successors a million years hence, 
for example, will be less coarse and barbarous than we 
are at present: the law of progress governs all the 
worlds, and, moreover, the physical constitution of the 
planet Mars is less dense than our own. 

There is no need to despair of entering some day 
into communication with thsse unknown beings. The 
luminous points that have been observed are no signals, 
but high summits or light clouds illuminated by the 
rising or setting sun. But the idea of communication 
with them in the future is no more audacious and no 
less scientific than the invention of spectral analysis, 
X-rays, or wireless telegraphy. 

We may suppose that the study of astronomy is 
further advanced in Mars than on the Earth, because 
humanity itself has advanced further, and because the 
starry sky is far finer there, far easier to study, owing 
to the limpidity of its pure, clear atmosphere. 

Two small moons (hardly larger than the city of 
Paris) revolve rapidly round Mars; they are called 
Phobos and Deimos. The former, at a distance of 

142 



THE PLANETS 

6,000 kilometers (3,730 miles) from the surface, accom- 
plishes its revolution rapidly, in seven hours, thirty-nine 
minutes, and thus makes the entire circle of the Heavens 
three times a day. The second gravitates at 20,000 kilo- 
meters (12,400 miles), and turns round its center of at- 
traction in thirty hours and eighteen minutes. These 
two satellites were discovered by Mr. Hall, at the 
University of Washington, in the month of August, 

1877. 

Among the finest and most interesting of the celes- 
tial phenomena admired by the Martians, at certain 
epochs of the year, — now at night when the Sun has 
plunged into his fiery bed, now in the morning, a little 
before the aurora, — is a magnificent star of first magni- 
tude, never far removed from the orb of day, which pre- 
sents to them the same aspects as does Venus to our- 
selves. This splendid orb, which has doubtless received 
the most flattering names from those who contemplate 
it, this radiant star of a beautiful greenish blue, courses 
in space accompanied by a little satellite, sparkling like 
some splendid diamond, after sunset, in the clear sky of 
Mars. This superb orb is the Earth, and the little star 
accompanying it is the Moon. 

Yes, to the Martians our Earth is a star of the morn- 
ing and evening; doubtless they have determined her 



ASTRONOMY FOR AMATEURS 




Fig. 44. — The Earth viewed from Mars. 

phases. Many a vow, and many a hope must have 
been wafted toward her, more than one broken heart 
must have permitted its unreaUzed dreams to wander 

144 



THE PLANETS 

forth to our planet as to an abode of happiness where 
all who have suffered in their native world might find a 
haven. But our planet, alas! is not as perfect as they 
imagine. 

We must not dally upon Mars, but hasten our celes- 
tial excursion toward Jupiten 



145 



CHAPTER VI 
THE PLANETS 

B, — Jupiter, Saturn, Uranus, Neptune. 

Before we attack the giant world of our system, we 
must halt for a few moments upon the minor planets 
which circulate between the orbit of Mars and that of 
Jupiter. These minute asters, little worlds, the largest 
of which measures scarcely more than lOO kilometers 
(62 miles) in diameter, are fragments of cosmic matter 
that once belonged to a vast ring, formed at the time 
when the solar system was only an immense nebula; 
and which, instead of condensing into a single globe 
coursing between Mars and Jupiter, split up into a con= 
siderable quantity of particles constituting at the present 
time the curious and highly interesting Republic of the 
Asteroids. 

These lilliputian worlds at first received the names 
of the more celebrated of the minor mythological divini- 
ties — Ceres, Pallas, Juno, Vesta, etc., but as they rapidly 
increased in number, it was found necessary to call them 
by modern, terrestrial names, and more than one daugh- 

146 



THE PLANETS 

ter of Eve, the Egeria of some astronomer, now has 
her name inscribed in the Heavens. The first minor 
planet v^as discovered on the first day of the nineteenth 
century, January i, 1801, by Piazzi, astronomer at 
Palermo. While he w^as observing the small stars in 
the constellation of the Bull beneath the clear Sicilian 
skies, this famous astronomer noticed one that he had 
never seen before. 

The next night, directing his telescope to the same 
part of the Heavens, he perceived that the fair unknown 
had moved her station, and the observations of the fol- 
lowing days left him no doubt as to the nature of the 
visitor: she was a planet, a wandering star among the 
constellations, revolving round the Sun^ This new- 
comer was registered under the name of Ceres. 

Since that epoch several hundreds of them have 
been discovered, occupying a zone that extends over a 
space of more than 400 million kilometers (249,000,000 
miles). These celestial globules are invisible to the 
naked eye, but no year passes without new and numerous 
recruits being added to the already important catalogue 
of these minute asters by the patient observers of the 
Heavens. To-day, they are most frequently discovered 
by the photographic method of following the displace- 
ment of the tiny moving points upon an exposed sensi- 
tive plateo 

11 147 



ASTRONOMY FOR AMATEURS 



JUPITER 

And now let us bow respectfully before Jupiter, the 
giant of the worlds. This glorious planet is indeed 
King of the Solar System. 

While Mercury measures only 4,750 kilometers 
(2,946 miles) in diameter, and Mars 6,728 (4,172), 
Jupiter is no less than 140,920 kilometers (87,400 miles) 
in breadth; that is to say, eleven times larger than the 
Earth. He is 442,500 kilometers (274,357 miles) in 
circumference. 

In volume he is equivalent to 1,279 terrestrial globes; 
hence he is only a million times smaller than the Sun. 
The previously described planets of our system, Mer- 
cury, Venus, the Earth, and Mars combined, would 
form only an insignificant mass in comparison with this 
colossus. A hundred and twenty-six Earths joined 
into one group would present a surface whose extent 
would still not be quite as vast as the superficies of this 
titanic world. This immense globe weighs 310 times 
more than that which we inhabit. Its density is only 
the quarter of our own; but weight is twice and a half 
times as great there as here. The constituents of things 
and beings are thus composed of materials lighter than 
those upon the Earth; but, as the planet exerts a force 

148 



THE PLANETS 

of attraction twice and a half times as powerful, they 
are in reality heavier and weigh more. A graceful 
maiden weighing fifty kilograms would if transported 
to Jupiter immediately be included in the imposing 
society of the *' Hundred Kilos." 

Jupiter rotates upon himself with prodigious rapidity. 

He accomplishes his diurnal revolution in less than ten 

i 
hours4^ There the day lasts half as long as here, and, 

while we reckoned fifteen days upon our calendar, the 

Jovian would count thirty-six. As Jupiter's year equals 

nearly twelve of ours, the almanac of that planet would 

contain 10,455 days! Obviously, our pretty little pocket 

calendars would never serve to enumerate all the dates 

in this vast world. 

This splendid globe courses in space at a distance 
of 775,000,000 kilometers (480,500,000 miles) from the 
Sun. Hence it is five times (5.2) as remote from the orb 
of day as our Earth, and its orbit is five times vaster than 
our own. At that distance the Sun subtends a diameter 
five times smaller than that which we see, and its surface 
is twenty-seven times less extensive; accordingly this 
planetary abode receives on an average twenty-seven 
times less light and heat than we obtain. 

In the telescope Jupiter presents an aspect analogous 
to that likely to be exhibited by a world covered with 
clouds, and enveloped in dense vapors (Fig. 45). 

149 



ASTRONOMY FOR AMATEURS 

It is, in fact, the seat of formidable perturbations, 
of strange revolutions by which it is perpetually con- 
vulsed, for although of more ancient formation than 
the Earth, this celestial giant has not yet arrived at the 
stable condition of our dwelling-place. Owing to its 




Fig. 45. — Telescopic aspect of Jupiter. 

considerable volume, this globe has probably preserved 
its original heat, revolving in space as an obscure Sun, 
but perhaps still burning. In it we see what our own 
planet must have been in its primordial epoch, in the 
pristine times of terrestrial genesis. 

150 



THE PLANETS 

Since its orbital revolution occupies nearly twelve 
years, Jupiter comes back into opposition with the Sun 
every 399 days, i. e.^ i year, 34 days, that is with one 
month and four days' delay each year. At these periods 
it is located at the extremity of a straight line which, 
passing by the Earth, is prolonged to the Sun. These 
are the epochs to be selected for observation. It shines 
then, all night, like some dazzling star of the first magni- 
tude, of excessive whiteness: nor can it be confounded 
either w4th Venus, more luminous still ffor she is never 
visible at midnight, in the full South, but is South-w^est 
in the evening, or South-east in the morning), nor with 
Mars, whose fires are ruddy. 

In the telescope, the immense planet presents a 
superb disk that an enlargement of forty times shows us 
to be the same size to all appearance as that of the Moon 
seen with the unaided eye. Its shape is not absolutely 
spherical, but spheroid — that is, flattened at the poles. 
The flattening is yy. 

We know that the Earth's axis dips a certain quantity 
on the plane of her orbit, and that it is this inclination 
that produces the seasons. Now it is not the same for 
Jupiter. His axis of rotation remains almost vertical 
throughout the course of his year, and results in the 
complete absence of climates and seasons. There is 
neither glacial zone, nor tropic zone; the position of 

151 



ASTRONOMY FOR AMATEURS 

Jupiter is eternally that of the Earth at the season of the 
equinox, and the vast world enjoys, as it were, perpetual 
spring. It knows neither the hoar-frost nor the snows 
of winter. The heat received from the Sun diminishes 
gradually from the equator to the poles without abrupt 
transitions, and the duration of day and night is equal 
there throughout the entire year, under every latitude. 
A privileged world, indeed! 

It is surrounded by a very dense, thick atmosphere, 
which undergoes more extensive variations than could 
be produced by the Sun at such a distance. Spectral 
analysis detects a large amount of water-vapor, showing 
that this planet still possesses a very considerable quan- 
tity of intrinsic heat. 

Most conspicuous upon this globe are the larger or 
smaller bands or markings (gray and white, sometimes 
tinted yellow, or of a maroon or chocolate hue) by which 
its surface is streaked, particularly in the vicinity of the 
equator. These different belts vary, and are constantly 
modified, either in form or color. Sometimes, they are 
irregular, and cut up; at others they are interspersed 
with more or less brilliant patches. These patches are 
not affixed to the surface of the globe, like the seas and 
continents of the Earth; nor do they circulate round 
the planet like the satellites, in more or less elongated 
and regular revolutions, but are relatively mobile, like 

152 



THE PLANETS 

our clouds in the atmosphere, while observation of their 
motion does not give the exact period of the rotation of 
Jupiter. Some only appear upon the agitated disk to 
vanish very quickly ; others subsist for a considerable 
period. 

One has been observed for over a quarter of a cen- 
tury, and appears to be almost immobile upon this 
colossal globe. This spot, w^hich v/as red at its first 
appearance, is now pale and ghostly. It is oval {vide 
Fig. 45) and measures 42,000 kilometers (26,040 miles) 
in length by 15,000 kilom. (9,300 m.) in width. Hence 
it is about four times as long as the diameter of our 
Earth; that is, relatively to the size of Jupiter, as are 
the dimensions of Australia in proportion to our globe. 
The discussion of a larger number of observations leads 
us to see in it a sort of continent in the making, a scoria 
recently ejected from the mobile and still liquid and 
heated surface of the giant Jupiter. The patch, however, 
oscillates perceptibly, and appears to be a floating island. 

We must add that this vast world, like the Sun, does 
not rotate all in one period. Eight different currents can 
be perceived upon its surface. The most rapid is that 
of the equatorial zone, which accomplishes its revolu- 
tion in 9 hours, 50 minutes, 29 seconds. A point situated 
on the equator is therefore carried forward at a speed of 
12,500 meters (7 miles) per second, and it is this giddy 



ASTRONOMY FOR AMATEURS 

velocity of Jupiter that has produced the flattening of 
the poles. From the equator to the poles, the swiftness 
of the currents diminishes irregularly, and the difference 
amounts to about five minutes between the movement 
of the equatorial stream, and that of the northern and 
southern currents. But what is more curious still is 
that the velocity of one and the same stream is subject 
to certain fluctuations; thus, in the last quarter of a 
century, the speed of the equatorial current has pro- 
gressively diminished. In 1879, the velocity was 9 hours, 
49 minutes, 59 seconds, and now it is, as we have already 
seen, 9 hours, 50 minutes, 29 seconds, which represents 
a substantial reduction. The rotation of the red patch, 
at 25 degrees of the southern latitude, is eff'ected in 
9 hours, 55 minutes, 40 seconds. 

We are confronted with a strange and mysterious 
world. It is the world of the future. 

This giant gravitates in space accompanied by a 
suite of five satellites. These are: 

Names. Distance from surface of Jupiter. Time of revolution. 
Kilometers. Miles. Days. Hours. 

5 200,000 124,000 II 

1. lo 430,000 266,000 i 18 

2. Europa 682,000 422,840 3 13 

3. Ganymede 1,088,000 674,560 7 4 

4. Callisto 1,914,000 1,186,680 16 16 

The four principal satellites of Jupiter were dis- 
covered at the same time, on the same evenings (Jan- 

154 



THE PLANETS 

uary 7 and 8, 1610), by the two astronomers who were 
pointing their telescopes at Jupiter. GaHleo in Italy, 
and Simon Marius in Germany. 

On September 9, 1892, Mr. Barnard, astronomer of 
the Lick Observatory, California, discovered a new 
satellite, extremely minute, and very near the enormous 
planet. It has so far received no name, and is known 
as the fifth, although the four principal are numbered 
in the order of their distances. 




Fig. 46. — Jupiter and his four principal satellites. 

The four classical satellites are visible in the smallest 
instruments (Fig. 46) : the third is the most volumi- 
nous. 

Such is the splendid system of the mighty Jupiter. 
Once, doubtless, this fine planet illuminated the troop of 
worlds that derived their treasure of vitality from him 
with his intrinsic light: to-day, however, these moons 
in their turn shed upon the extinct central globe the 
pale soft light which they receive from our solar focus. 



ASTRONOMY FOR AMATEURS 

illuminating the brief Jovian nights (which last less than 
five hours, on account of the twilight) with their variable 
brilliancy. 

At the distance of the first satellite, Jupiter exhibits 
a disk fourteen hundred times vaster than that of the Full 
Moon! What a dazzling spectacle, what a fairy scene 
must the enormous star afford to the inhabitants of that 
tiny world! And what a shabby figure must our Earth 
and Moon present in the face of such a body, a real 
miniature of the great solar system! 

Our ancestors were well inspired when they attribu- 
ted the sovereignty of Olympus to this majestic planet. 
His brilliancy corresponds with his real grandeur. His 
dominion in the midnight Heavens is unique. Here 
again, as for Venus, Mars, and Mercury, astronomy has 
created the legend of the fables of mythology. 

Let us repeat in conclusion that our Earth becomes 
practically invisible for the inhabitants of the other 
worlds beyond the distance of Jupiter. 

SATURN 

Turn back now for a moment to the plan of the 
Solar System. 

We had to cross 775 million kilometers (480,000,000 
miles) when we left the Sun, in order to reach the im- 

156 



THE PLANETS 

mense orb of Jupiter, which courses in space at 626 
milUon kilometers (388,000,000 miles) from the terres- 
trial orbit. From Jupiter we had to traverse a distance 
of 646 million kilometers (400,000,000 miles) in order to 
reach the marvelous system of Saturn, where our eyes 
and thoughts must next alight. 

Son of Uranus and Vesta, Saturn was the God of 
Time and Fate. He is generally represented as an aged 
man bearing a scythe. His mythological character is 
only the expression of his celestial aspect, as we have 
seen for the brilliant Jupiter, for the pale Venus, the 
ruddy Mars, and the agile Mercury. The revolution 
of Saturn is the slowest of any among the planets known 
to the ancients. It takes almost thirty years for its 
accomplishment, and at that distance the Saturnian 
world, though it still shines with the brilliancy of a star 
of the first magnitude, exhibits to our eyes a pale and 
leaden hue. Here is, indeed, the god of Time, with 
slow and almost funereal gait. 

Poor Saturn won no favor with the poets and astrol- 
ogers. He bore the horrid reputation of being the 
inexhaustible source of misfortune and evil fates, — 
whereof he is wholly innocent, troubling himself not at 
all with our world nor its inhabitants. 

This world travels in the vastness of the Heavens at 
a distance of 1,421 million kilometers (881,000,000 miles) 



ASTRONOMY FOR AMATEURS 

from the Sun. Hence it is ten times farther from the orb 
of day than the Earth, though still illuminated and gov- 
erned by the Sun-God. Its gigantic orbit is ten times 
larger than our own. 

Its revolution round the Sun Is accomplished in 
10,759 days, /. ^., 29 years, 167 days, and as this strange 
planet rotates upon itself v^ith great rapidity in 10 hours, 
15 minutes, its year comprises no less than 25,217 days. 
What a calendar! The Saturnians must needs have a 
prodigious memory not to get hopelessly involved in this 
interminable number of days. A curious world, where 
each year stands for almost thirty of our own, and where 
the day is more than half as short again as ours. But 
we shall presently jfind other and more extraordinary 
differences on this planet. 

In the first place it is nearly nine and a half times 
larger than our world. It is a globe, not spherical, but 
spheroidal, and the flattening of its poles, which is one- 
tenth, exceeds that of all the other planets, even Jupiter. 
It follows that its equatorial diameter is 112,500 kilo- 
meters (69,750 miles), while its polar diameter measures 
only 110,000 (68,200). 

In volume, Saturn is 719 times larger than the Earth, 
but its density is only xV/o ^^ ^^^* own; i. ^., the mate- 
rials of which it is composed are much less heavy, so 
that it weighs only Q2 times more than our Earth. Its 

158 



THE PLANETS 

surface is 85 times vaster than that of the Earth, no 
insignificant proportion. 

The dipping of Saturn's axis of rotation is much the 
same as our own. Hence we conclude that the sea- 
sons of this planet are analogous to ours in relative 
intensity. Only upon this far-off world each season 
lasts for seven years. At the distance at which it gravi- 




FiG. 47. — Saturn. 

tates in space, the heat and light which it receives from 
the Sun are 90 times less active than such as reach our- 
selves; but it apparently possesses an atmosphere of 
great density, which may be constituted so that the heat 
is preserved, and the planet maintained in a calorific 
condition but little inferior to our own. 

In the telescope, the disk of Saturn exhibits large 
belts that recall those of Jupiter, though they are broader 

159 



ASTRONOMY FOR AMATEURS 

and less accentuated (Fig. 47). There are doubtless 
zones of clouds or rapid currents circulating in the atmos- 
phere. Spots are also visible whose displacement assists 
in calculating the diurnal motions of this globe. 

The most extraordinary characteristic of this strange 
world is, however, the existence of a vast ring, which is 
almost flat and very large, and entirely envelops the body 
of the planet. It is suspended in the Saturnian sky, 
like a gigantic triumphal arch, at a height of some 
20,000 kilometers (12,400 miles) above the equator. 
This splendid arch is circular, like an immense crown 
illuminated by the Sun. From here we only see it 
obliquely, and it appears to us elliptical; a part of the 
ring seems to pass in front of Saturn, and its shadow 
is visible on the planet, while the opposite part passes 
behind. 

This ring, which measures 284,000 kilometers 
(176,080 miles) in diameter, and less than 100 kilometers 
(62 miles) in breadth, is divided into three distinct zones: 
the exterior is less luminous than the center, which is 
always brighter than the planet itself; the interior is 
very dark, and spreads out like a dusky and faintly 
transparent veil, through which Saturn can be distin- 
guished. 

What is the nature of these vast concentric circles 
that surround the planet with a luminous halo ? They 

160 



THE PLANETS 

are composed of an innumerable number of particles, 
of a quantity of cosmic fragments, which are swept off 
in a rapid revolution, and gravitate round the planet 
at variable speed and distance. The nearer particles 
must accomplish their revolution in 5 hours, 50 minutes, 
and the most distant in about 12 hours, 5 minutes, to 




Fig. 48. — Varying perspective of Saturn's Rings, as seen 
from the Earth. 



prevent them from being merged in the surface of Saturn : 
their own centrifugal force sustains them in space. 

With a good glass the effect of these rings is most 
striking, and one can not refrain from emotion on con- 
templating this marvel, whereby one of the brothers of 
our terrestrial country is crowned with a golden diadem. 

161 



ASTRONOMY FOR AMATEURS 

Its aspects vary with its perspective relative to the Earth, 
as may be seen from the subjoined figure (Fig. 48). 

We must not quit the Saturnian province w^ithout 
mentioning the eight sateUites that form his splendid 
suite: 

Names. Distance from the planet. Time of revolution. 

Kilometers. ]\Iiles. Days. Hours. Minutes. 

1. Mimas 207,000 128,340 22 37 

2. Enceladus 257,600 159,712 i 8 53 

3. Tethys 328,800 203,856 i 21 18 

4. Dione 421,200 261,144 ^ ^7 4^ 

5. Rhea 588,400 364,808 4 12 25 

6. Titan 1,364,000 845,680 15 22 41 

7. Hyperion 1,650,000 1,023,000 21 6 39 

8. Japhet 3,964,000 2,457,680 79 7 54 

Here is a marvelous system, with, what is more, eight 
different kinds of months for the inhabitants of Saturn; , 
eight moons with constantly varying phases juggling 
above the rings! 

Now we shall cross at a bound the 1,400 million 
kilometers (868,000,000 miles) that separate us from 
the last station but one of the immense solar system. 

URANUS 

On March 13, 1781, William Herschel, a Hanoverian 
astronomer who had emigrated to England, having 
abandoned the study of music to devote himself to the 
sublime science of the Heavens, was observing the vast 

162 



THE PLANETS 

fields with their constellations of golden stars, when he 
perceived a luminous point that appeared to him to 
exceed that of the other celestial luminaries in diameter. 
He replaced the magnification of his telescope by more 
powerful eye-pieces, and found that the apparent di- 
ameter of the orb increased proportionately with the 
amplification of the power, which does not happen in 
the case of stars at infinite distance. His observations 
on the follovv^ng evenings enabled him to note the slow 
and imperceptible movement of this star upon the 
celestial sphere, and left him in no further doubt: 
there was no star, but some much nearer orb, in all 
probability a comet, for the great astronomer dared not 
predict the discovery of a new planet. And it was thus, 
under the name of cometary orb, that the seventh child 
of the Sun was announced. The astronomers sought 
to determine the motions of the new arrival, to dis- 
cover for it an elliptical orbit such as most com.ets have. 
But their eff'orts were vain, and after several months' 
study the conclusion was reached that here was a new 
planet, throwing back the limits of the solar system to 
a point far beyond that of the Saturnian frontier, as 
admitted from antiquity. 

This new world received the name of Uranus, father 
of Saturn, his nearest neighbor in the solar empire. 
Uranus shines in the firmament as a small star of 
12 163 



ASTRONOMY FOR AMATEURS 

sixth magnitude, invisible to the unaided eye for normal 
sight, at a distance of 2,831,000,000 kilometers (1,755,- 
000,000 miles) from the Sun. Smaller than Jupiter and 
Saturn, this planet is yet larger than Mercury, Venus, 
Mars, and the Earth together, thus presenting pro- 
portions that claim our respect and admiration. 

His diameter may be taken at about 55,000 kilometers 
(34,200 miles), that is, rather more than four times the 
breadth of the terrestrial diameter. Sixty-nine times 
more voluminous than the Earth, and seventeen times 
more extensive in surface, this nev^ w^orld is much less 
than our own in density. The matter of w^hich it is 
composed is nearly five times lighter than that of our 
globe. 

Spectral analysis shoves that this distant planet is 
surrounded w^ith an atmosphere very different from 
that which we breathe, enclosing gases that do not exist 
in ours. 

The Uranian globe courses over the fields of infinity 
in a vast orbit seventeen times larger than our own, and 
its revolution lasts 36,688 days, /'. ^., 84 years, 8 days. 
It travels slowly and sadly under the pale and languishing 
rays of the Sun, which sends it nearly three hundred 
times less of light and heat than we receive. At this 
distance the solar disk would present a diameter seven- 
teen times smaller than that which we admire, and a 

164 



THE PLANETS 

surface three hundred times less vast. A dull world 
indeed! And what an interminable year! The idle 
people who are in the habit of being bored must find 
time even longer upon Uranus than upon our little 
Earth, where the days pass so rapidly. And if matters 
are arranged there as here, a babe of a year old, begin- 
ning to babble in its nurse's arms, would already have 
lived as long as an old man of eighty-four in this world. 
But what most seriously complicates the Calendar 
of the Uranians is the fact that the four moons which 
accompany the planet accomplish their revolution in 
four different kinds of months, in two, four, eight, and 
thirteen days, as is shown in the following table: 

Distance from the planet. Time of revolution. 

Kilometers. Miles. Days. Hours. INIinutes. 

1. Ariel 196,000 121,520 2 12 29 

2. Umbriel ...... , 276,000 171,120 4 3 27 

3. Titania 450,000 279,000 8 16 56 

4. Oberon 600,000 372,000 13 11 7 

The most curious fact is that these satellites do not 
rotate like those of the other planets. While the moons 
of the Earth, Mars, Jupiter, and Saturn accomplish 
their revolution from east to west, the satellites of 
Uranus rotate in a plane almost perpendicular to the 
ecliptic, and it is doubtless the same for the rotation 
of the planet. 

If we had to quit the Earth, and fixate ourselves upon 

165 



ASTRONOMY FOR AMATEURS 

another world, we should prefer Mars to Uranus, where 
everything must be so different from terrestrial arrange- 
ments ? But who knows ? Perhaps, after all, this planet 
might afford us some agreeable surprises. // ne faut 
jurer de rien, 

NEPTUNE 

And here we reach the frontier of the Solar System, 
as actually known to us. In landing on the world of 
Neptune, which circles through the Heavens in eternal 
twilight at a distance of more than four milliard kilo- 
meters (2,480,000,000 miles) from the common center 
of attraction of the planetary orbs, we once again admire 
the prodigies of science. 

Uranus was discovered with the telescope, Neptune 
by calculation. In addition to the solar influence, the 
worlds exert a mutual attraction upon each other that 
slightly deranges the harmony ordered by the Sun. The 
stronger act upon the weaker, and the colossal Jupiter 
alone causes many of the perturbations in our great 
solar family. Now during regular observations of the 
position of Uranus in space, some inexplicable irregu- 
larities were soon perceived. The astronomers having 
full faith in the universality of the law of attraction, 
could not do otherwise than attribute these irregularities 

166 



THE PLANETS 

to the influence of some unknown planet situated even 
farther off. But at what distance ? 

A very simple proportion, known as Bode's law, 
has been observed, which indicates approximately the 
relative distances of the planets from the Sun. It is 
as follows: Starting from o, write the number 3, and 
double successively, 

o 3 6 12 24 48 96 192 384. 

Then, add the number 4 to each of the preceding 
figures, which gives the following series: 

4 7 10 16 28 52 100 196 388. 

Now it is a very curious fact that if the distance 
between the Earth and the Sun be represented by 10, 
the figure 4 represents the orbit of Mercury, 7 that of 
Venus, 16 of Mars; the figure 28 stands for the medium 
distance of the minor planets; the distances of Jupiter, 
Saturn, and Uranus agree with 52, 100, and 196. 

The immortal French mathematician Le Verrier, 
who pursued the solution of the Uranian problem, sup- 
posed naturally that the disturbing planet must be at 
the distance of 388, and made his calculations accord- 
ingly. Its direction in the Heavens was indicated by 
the form of the disturbances; the orbit of Uranus bulg- 
ing, as it were, on the side of the disturbing factor. 

On August 31, 1846, Le Verrier announced the 
position of the ultra-Uranian planet, and on September 

167 



ASTRONOMY FOR AMATEURS 

23d following, a German astronomer, Galle, at the 
Observatory of Berlin, who had just received this in- 
telligence, pointed his telescope toward the quarter of 
the Heavens designated, and, in fact, attested the pres- 
ence of the new orb. Without quitting his study table, 
Le Verrier, by the sole use of mathematics, had de- 
tected, and, as it were, touched at pen's point the mys- 
terious stranger. 

Only, it is proved by observation and calculation 
that it is less remote than was expected from the pre- 
ceding law, for it gravitates at a distance of 300, given 
that from the Earth to the Sun as 10. 

This planet was called Neptune, god of the seas, 
son of Saturn, brother of Jupiter. The name is well 
chosen, since the King of the Ocean lives in darkness in 
the depths of the sea, and Le Verrier's orb is also plunged 
in the semi-obscurity of the depths of the celestial ele- 
ment. But it was primarily selected to do justice to an 
English astronomer, Adams, who had simultaneously 
made the same calculations as Le Verrier, and obtained 
the same results — without publishing them. His work 
remained in the records of the Greenwich Observ- 
atory. 

The English command the seas, and wherever they 
dip their finger into the water and find it salt, they feel 
themselves **at home," and knov/ that '^Neptune's tri- 

168 



THE PLANETS 

dent is the scepter of the world/' hence this compli= 
mentary nomenclature. 

Neptune is separated bv a distance of four mil- 
liards, four hundred million kilometers from the solar 
center. 

At such a distance, thirty times greater than that 
which exists between the Sun and our world, Neptune 
receives nine hundred times less light and heat than 
ourselves; /. ^., Spitzbergen and the polar regions of our 
globe are furnaces compared with what must be the 
Neptunian temperature. Absolutely invisible to the 
unaided eye, this world presents in the telescope the 
aspect of a star of the eighth magnitude. With powerful 
magnifications it is possible to measure its disk, which 
appears to be slightly tinged with blue. Its diameter is 
four times larger than our own, and measures about 
48,000 kilometers (29,900 miles), its surface is sixteen 
times vaster than that of the Earth, and to attain its 
volume we should have to put together fifty-five globes 
similar to our own. Weight at its surface must be about 
the same as here, but its medium density is only ^ that 
of the Earth. 

It gravitates slowly, dragging itself along an orbit 
thirty times vaster than that of our globe, and its revolu- 
tion takes 164 years, 281 days, /. e., 164 years, 9 months. 
A single year of Neptune thus covers several generations 

169 



ASTRONOMY FOR AMATEURS 

of terrestrial life. Existence must, indeed, be strange 
in that tortoise-footed world! 

While in their rotation period, Mercury accom- 
plishes 47 kilom^eters (29! miles) per second, and the 
Earth 29^ (i8i miles), Neptune rolls along his immense 
orbit at a rate of only 5^ kilometers (about 3^ miles) 
per second. 

The vast distance that separates us prevents our 
distinguishing any details of his surface, but spectral 
analysis reveals the presence of an absorbent atmos- 
phere in which are gases unknown to the air of our 
planet, and of which the chemical composition resem- 
bles that of the atmosphere of Uranus. 

One satellite has been discovered for Neptune. It 
has a considerable inclination, and rotates from east to 
west. 

And here we have reached the goal of our inter- 
planetary journey. After visiting the vast provinces 
of the solar republic, we feel yet greater admiration and 
gratitude toward the luminary that governs, warms, 
and illuminates the worlds of his system. 

In conclusion, let us again insist that the Earth, — 
a splendid orb as viewed from Mercury, Venus, and 
Mars, — begins to disappear from Jupiter, where she 
becomes no more than a tiny spark oscillating from 

170 



THE PLANETS 

s.ce to side of the Sun, and occasionally passing in front 
of him as a small black dot. From Saturn the visibility 
of our planet is even more reduced. As to Uranus and 
Neptune, we are invisible there, at least to eyes con- 
structed like our own. We do not possess in the Universe 
the importance with which we would endow ourselves. 
Neptune up to the present guards the portals of our 
celestial system; we will leave him to watch over the 
distant frontier; but before returning to the Earth, we 
must glance at certain eccentric orbs, at the mad, capri- 
cious comets, which imprint their airy flight upon the 
realms of space. 



171 



CHAPTER VII 

THE COMETS 

Shooting Stars, Bolides, Uranoliths or Meteoric Stones 

What marvels have been reviewed by our dazzled 
eyes since the outset of these discussions! We first 
surveyed the magnificent host of stars that people the 
vast firmament of Heaven; next we admired and won- 
dered at suns very differently constituted from our own; 
then returning from the depths of space, crossing at a 
bound the abyss that separates us from these mys- 
terious luminaries, the distant torches of our somber 
night, terrible suns of infinity, we landed on our own 
beloved orb, the superb and brilliant day-star. Thence 
we visited his celestial family, his system, in which our 
Earth is a floating island. But the journey would be 
incomplete if we omitted certain more or less vagabond 
orbs, that occasionally approach the Sun and Earth, 
some of which may even collide with us upon their celes- 
tial path. These are in the first place the comets, then 
the shooting stars, the fire-balls, and meteorites. 

Glittering, swift-footed heralds of Immensity, these 
172 



THE COMETS 

comets with golden wings glide lightly through Space, 
shedding a momentary illumination by their presence. 
Whence come they ? Whither are they bound ? 

What problems they propound to us, when, as in 
some beautiful display of pyrotechnics, the arch of 
Heaven is illuminated with their fantastic light! 

But first of all — ^what is a Comet ? 

If instead of living in these days of the telescope, of 
spectrum analysis, and of astral photography, we were 
anterior to Galileo, and to the liberation of the human 
spirit by Astronomy, we should reply that the comet is 
an object of terror, a dangerous menace that appears 
to mortals in the purity of the immaculate Heavens, to 
announce the most fatal misfortunes to the inhabitants 
of our planet. Is a comet visible in the Heavens ? The 
reigning prince may make his testament and prepare to 
die. Another apparition in the firmament bodes war, 
famine, the advent of grievous pestilence. The astrol- 
ogers had an open field, and their fertile imagination 
might hazard every possible conjecture, seeing that 
misfortunes, great or small, are not altogether rare in 
this sublunar world. 

How many intellects, and those not the most vulgar, 
from antiquity to the middle of the last century cursed 
the apparition of these hirsute stars, which brought 
desolation to the heart of man, and poured their fatal 



ASTRONOMY FOR AMATEURS 

effluvia upon the head of poor Humanity. The history 
of the superstitions and fears that they inspired of old 
would furnish matter for the most thrilling of romances. 
But, on the other hand, the volume would be little flat- 
tering to the common-sense of our ancestors. Despite 
the respect we owe our forefathers, let us recall for a 




Fig. 49. — The Great Comet of 1858. 

moment the prejudices attaching to the most famous 
comets whose passage, as observed from the Earth, has 
been preserved to us in history. 

Without going back to the Deluge, we note that the 
Romans established a relation between the Great Comet 



THE COMETS 

of 43 B. c. and the death of Caesar, who had been assas- 
sinated a few months previously. It was, they asserted, 
the soul of their great Captain, transported to Heaven 
to reign in the empyrean after ruling here below. Were 
not the Emperors Lords of both Earth and Heaven ? 

We must in justice recognize that certain more in- 
dependent spirits emancipated themselves from these 
superstitions, and we may cite the reply of Vespasian to 
his friends, who were alarmed at the evil presage of a 
flaming comet: *'Fear nothing," he said, ''this bearded 
star concerns me not; rather should it threaten my 
neighbor the King of the Parthians, since he is hairy 
and I am bald." 

In the year 837 one of these mysterious visitants 
appeared in the Heavens. It was in the reign of Lewis 
the Debonair. Directly the King perceived the comet, 
he sent for an astrologer, and asked what he was to con- 
clude from the apparition. As the answers were un- 
satisfactory he tried to avert the augury by prayers to 
Heaven, by ordaining a general fast to all his Court, and 
by building churches. Notwithstanding, he died three 
years later, and the historians profited by this slender 
coincidence to set up a correlation between the fatal star 
and the death of the Sovereign. This comet, famous 
in history, is no other than that of Halley, in one of its 
appearances. 

175 



ASTRONOMY FOR AMATEURS 

This comet returned to explore the realms near the 
Sun in 1066, at the moment when William of Normandy 
was undertaking the Conquest of England, and was mis- 
guided enough to go across and reign in London, instead 
of staying at home and annexing England, thus by his 
action founding the everlasting rivalry between France 
and this island. A beneficial influence was attributed 
to the comet in the Battle of Hastings. 

A few centuries later it again came into sight from 
the Earth, in 1456, three years after the capture of Con- 
stantinople by the Turks. Feeling ran high in Europe, 
and this celestial omen was taken for a proof of the an- 
ger of the Almighty. The moment was decisive; the 
Christians had to be rescued from a struggle in which 
they were being worsted. At this conjuncture. Pope 
Calixtus resuscitated a prayer that had fallen into disuse, 
the Angelusy and ordered that the bells of the churches 
should be rung each day at noon, that the Faithful might 
join at the same hour in prayer against the Turks and 
the Comet. This custom has lasted down to our own 
day. 

Again, to the comet of 1500 was attributed the tem- 
pest that caused the death of Bartholomew Diaz, a 
celebrated Portuguese navigator, who discovered the 
Cape of Good Hope. 

In 1528 a bearded star of terrific aspect alarmed the 
176 



THE COMETS 

world, and the more serious spirits were influenced by 
this menacing comet, which burned in the Heavens hke 
*'a great and gory sword/' In a chapter on Celestial 
Monsters the celebrated surgeon Ambroise Pare de- 




FiG. 50. — What our Ancestors saw in a Comet. 

After Ambroise Pare (1^28). 

scribes this awful phenomenon in terms anything but 
seductive, or reassuring, showing us the menacing sword 
surrounded by the heads it had cut off (Fig. 50). 

Our fathers saw many other prodigies in the skies; 
177 




Cavalry, and a bloody branch crossing the sun, June ii, 1554. 

Fig. 51. — Prodigies seen in the Heavens by our Forefathers. 

178 



THE COMETS 

their descendants, less credulous, can study the facsimile 
reproduced in Fig. 51, of the drawings published in the 
year 1557 by Conrad Lycosthenes in his curious Book 
of Prodigies. 

So, too, it is asserted that Charles V renounced the 
jurisdiction of his Estates, which were so vast that ''the 
Sun never slept upon them," because he was terrified 
by the comet of 1556 which burned in the skies with an 
alarming brilliancy, into passing the rest of his days in 
prayer and devotion. 

It is certain that comets often exhibit very strange 
characteristics, but the imagination that sees in them 
such dramatic figures must indeed be lively. In the 
Middle Ages and the Renaissance these w^ere swords of 
fire, bloody crosses, flaming daggers, etc., all horrible 
objects ready to destroy our poor human race! 

At the time of the Romans, Pliny made some curious 
distinctions between them: ''The Bearded Ones let 
loose their hair like a majestic beard; the Javelin darts 
forth like an arrow; if the tail is shorter and ends in a 
point, it is called the Sword; this is the palest of all 
the Comets; it shines like a sword, without rays; the 
Plate or Disk is named in conformity with its figure; its 
color is amber, the Barrel is actually shaped like a barrel, 
as it might be in smoke, with light streaming through it; 
the Horn imitates the figure of a horn erected in the sky, 
13 179 



ASTRONOMY FOR AMATEURS 

and the Lamp that of a burning flame; the Equine rep- 
resents a horse's mane, shaken violently with a circu- 
lar motion. There are bristled comets; these resemble 
the skins of beasts with the fur on them, and are sur- 
rounded by a nebulosity. Lastly, the tails of certain 
comets have been seen to menace the sky in the form of 
ance. 

These hairy orbs that appear in all directions, and 
whose trajectories are sometimes actually perpendicular 
to the plane of the ecliptic, appear to obey no regular 
law. Even in the seventeenth century the perspicacious 
Kepler had not divined their true character, seeing in 
them, like most of his contemporaries, emanations from 
the earth, a sort of vapor, losing itself in space. These 
erratic orbs could not be assimilated with the other 
members of our grand solar family where, generally 
speaking, everything goes on in regular order. 

And even in our own times, have we not seen the 
people terrified at the sight of a flaming comet ? Has 
not the end of the world by the agency of comets been 
often enough predicted ? These predictions are so to 
speak periodic; they crop up each time that the return 
of these cosmical formations is announced by the as- 
tronomers, and always meet with a certain number of 
timid souls who are troubled as to our destinies. 



l8o 



THE COMETS 

To-day we know that these wanderers are subject 
to the general laws that govern the universe. The 
great Newton announced that, like the planets, they 
were obedient to universal attraction; that they must 
follow an extremely elongated curve, and return period- 
ically to the focus of the ellipse. From the basis of 
these data Halley calculated the progress of the comet 
of 1682, and ascertained that its motions presented such 
similarity with the apparitions of 153 1 and 1607, that 
he believed himself justified in identifying them and in 
announcing its return about the year 1759. Faithful 
to the call made upon it, irresistibly attracted by the Orb 
of Day, the comet, at first pale, then ardent and incan- 
descent, returned at the date assigned to it by calcu- 
lation, three years after the death of the illustrious 
astronomer. Shining upon his grave it bore witness 
to the might of human thought, able to snatch the pro- 
foundest secrets from the Heavens! 

This fine comet returns every seventy-six years, to 
be visible from the Earth, and has already been seen 
twenty-four times by the astonished eyes of man. It 
appears, however, to be diminishing in magnitude. Its 
last appearance was in 1835, and we shall see it again 
in 1910, a little sooner than its average period, the at- 
traction of Jupiter having this time slightly accelerated 
its course, while in 1759 it retarded it. 

181 



ASTRONOMY FOR AMATEURS 

The comets thus follow a very elongated orbit, either 
elliptic, turning round the Sun, or parabolic, dashing 
out into space. In the first case, they are periodic 
(Fig. 52), and their return can be calculated. In the 
second they surprise us unannounced, and return to 
the abysses of eternity to reappear no more. 

Their speed is even greater than that of the planets; 
it is equivalent to this, multiplied by the square root 




Fig. 52. — The orbit of a Periodic Comet. 



of 2, that is to say by 1.414. Thus at the distance of 
the Earth from the Sun this velocity = 29,500 meters 
(18 miles) per second, multiplied by the above number, 
that is, 41,700 meters (over 25 miles). At the distance 
of Mercury it = 47 X 1.414 or 66,400 meters (over 
40 miles) per second. 

Among the numerous comets observed, w^e do not as 
yet knov^ more than some twenty of which the orbit has 
been determined. Periodicity in these bearded orbs 

182 



THE COMETS 

is thus exceptional, if we think of the innumerable multi- 
tude of comets that circle through the Heavens. Kepler 
did not exaggerate when he said "there are as many 
comets in the skies as there are fishes in the sea." These 
scouts of the sidereal world constitute a regular army, 
and if we are only acquainted with the dazzling generals 
clad in gold, it is because the more modest privates can 
only be detected in the telescope. Long before the 
invention of the latter, these wanderers in the firmament 
roamed through space as in our own day, but they defied 
the human eye, too weak to detect them. Then they 
were regarded as rare and terrible objects that no one 
dared to contemplate. To-day they may be counted by 
hundreds. They have lost in prestige and in originality; 
but science is the gainer, since she has thus endowed 
the solar system with new members. No year passes 
without the announcement of three or four new arrivals. 
But the fine apparitions that attract general attention 
by their splendor are rare enough. 

These eccentric visitors do not resemble the planets, 
for they have no opaque body like the Earth, Venus, 
Mars, or any of the rest. They are transparent nebu- 
losities, of extreme lightness, without mass nor density. 
We have just photographed the comet of the moment, 
July, 1903: the smallest stars are visible through its tail, 
and even through the nucleus.] 

183 



ASTRONOMY FOR AMATEURS 

They arrive in every direction from the depths of 
space, as though to reanimate themselves in the burning, 
luminous, electric solar center. 

Attracted by some potent charm toward this daz- 
zling focus, they come inquisitive and ardent, to warm 
themselves at its furnace. At first pale and feeble, they 
are born again when the Sun caresses them with his 
fervid heat. Their motions accelerate, they haste to 
plunge wholly into the radiant light. At length they 
burst out luminous and superb, when the day-star pene- 
trates them with his burning splendor, illuminates them 
with a marvelous radiance, and crowns them with glory. 
But the Sun is generous. Having showered benefits 
upon these gorgeous celestial butterflies that flutter 
round him as round some altar of the gods, he grants 
them liberty to visit other heavens, to seek fresh uni- 
verses. . . . 

The original parabola is converted into an ellipse, 
if the imprudent adventurer in returning to the Sun 
passes near some great planet, such as Jupiter, Saturn, 
Uranus, or Neptune, and suff'ers its attraction. It is 
then imprisoned by our system, and can no longer es- 
cape from it. After reenforcement at the solar focus, 
it must return to the identical point at which it felt the 
first pangs of a new destiny. Henceforward, it belongs 
to our celestial family, and circles in a closed curve. 

184 



THE COMETS 

otherwise, it is free to continue its rapid course toward 
other suns and other systems. 



As a rule, the telescope shows three distinct parts in 
a comet. There is first the more brilliant central point, 
or nucleus, surrounded by a nebulosity called the hair, 
or brush, and prolonged in a luminous appendix stretch- 
ing out into the tail. The head of the comet is the brush 
and the nucleus combined. 




Fig. 53. — The tails of Comets are opposed to the Sun. 

It is usually supposed that the tail of a comet follows 
it throughout the course of its peregrinations. Nothing 
of the kind. The appendix may even precede the 
nucleus; it is always opposite the Sun, — that is to say, it 
is situated on the prolongation of a straight line, starting 
from the Sun, and passing through the nucleus (Fig. 53). 
The tail does not exist, so long as the comet is at a 
distance from the orb of day; but in approaching the 
Sun, the nebulosity is heated and dilates, giving birth 

185 



ASTRONOMY FOR AMATEURS 

to those mysterious tails and fantastic streamers whose 
dimensions vary considerably for each comet. The 
dilations and transformations undergone by the tail 
suggest that they may be due to a repulsive force emana- 
ting from the Sun, an electric charge transmitted doubt- 
less through the ether. It is as though Phoebus blew 
upon them with unprecedented force. 

Telescopic comets are usually devoid of tail, even 
when they reach the vicinity of the Sun. They appear 
as pale nebulosities, rounded or oval, more condensed 
toward the center, without, however, showing any dis- 
tinct nucleus. These stars are only visible for a minute 
fraction of their course, when they reach a point not far 
from the Sun and the terrestrial orbit. 

The finest comets of the last century were those of 
1811, 1843, 1858, 1861, 1874, 1880, 1881, and 1882. 
The Great Comet of 181 1, after spreading terror over 
certain peoples, notably in Russia, became the provi- 
dence of the vine-growers. As the wine was particu- 
larly good and abundant that year, the peasants at- 
tributed this happy result to the influence of the celestial 
visitant. 

In 1843 one of these strange messengers from the 
Infinite appeared in our Heavens. It was so brilliant 
that it was visible in full dayHght on February 28th, 
alongside of the Sun. This splendid comet was ac- 

186 



THE COMETS 

companied by a marvelous rectilinear tail measuring 
300,000,000 kilometers (186,000,000 miles) in length, 
and its flight was so rapid that it turned the solar hemi- 
sphere at perihelion in two hours, representing a speed of 
550 kilometers (342 miles) a second. 

But the most curious fact is that this radiant ap- 
parition passed so near the Sun that it must have 
traversed its flames, and yet emerged from them safe 
and sound. 

Noteworthy also was the comet of 1858 (Fig. 49), 
discovered at Florence by Donati. Its tail extended to 
a length of 90,000,000 kilometers (55,900,000 miles), 
and its nucleus had a diameter of at least 900 kilo- 
meters (559 miles). It is a curious coincidence that the 
wine was remarkably excellent and abundant in that 
year also. 

The comet of 1861 almost rivaled the preceding. 

Coggia's Comet, in 1874, was also remarkable for its 
brilliancy, but was very inferior to the last two. Finally, 
the latest worthy of mention appeared in 1882. This 
magnificent comet also touched the Sun, traveling at a 
speed of 480 kilometers (299 miles) per second. It 
crossed the gaseous atmosphere of the orb of day, and 
then continued its course through infinity. On the day 
of, and that following, its perihelion, it could be detected 
with the unaided eye in full daylight, enthroned in the 

187 



ASTRONOMY FOR AMATEURS 

Heavens beside the dazzling solar luminary. For the 
rest, it was neither that of 1858 nor of 1861. 

Since 1882 we have not been favored with a visit 
from any fine comet; but we are prepared to give any 
such a reception worthy of their magnificence: first, 
because now that we have fathomed them we are no 
longer awestruck ; second, because we would gladly 
study them more closely. 

In short, these hirsute stars, whose fantastic ap- 
pearance impressed the imagination of our ancestors 
so vividly, are no longer formidable. Their mass is 
inconsiderable; they seem to consist mainly of the light- 
est of gases. Analysis of their incandescence reveals a 
spectrum closely resembling that of many nebulae; the 
presence of carbon is more particularly obvious. Even 
the nucleus is not solid, and is often transparent. 

It is fair to say that the action of a comet might be 
deleterious if one of these orbs were to arrive directly 
upon us. The transformation of motion into heat, and 
the combination of the cometary gases with the oxygen 
of our atmosphere might produce a conflagration, or a 
general poisoning of the atmosphere. 

But the coUision of a comet with a planet is almost 
an impossibility. This phenomenon could only occur 
if the comet crossed the planetary orbit at the exact 

188 



THE COMETS 

moment at which the planet was passing. When we 
think of the immensity of space, of the extraordinary 
length of way traversed by a world in its annual journey 
round the Sun, and the speed of its rotation, we see 
why this coincidence is hardly likely to occur. Thus, 
among the hundreds of comets catalogued, a few only 
cut the terrestrial orbit. One of them, that of 1832, 
traversed the path of our globe in the nights of October 
29 and 30 in that year; but the Earth only passed the 
same point thirty days later, and at the critical period 
was more than 80,000,000 kilometers (50,000,000 miles) 
away from the comet. 

On June 30, 1861, however, the Earth passed through 
the extremity of the tail of the Great Comet of that year. 
No one even noticed it. The effects were doubtless quite 
immaterial. 

In 1872 we were to collide with Biela's Comet, lost 
since 1852; now, as we shall presently see, we came with 
flying colors out of that disagreeable situation, because 
the comet had disintegrated, and was reduced to powder. 
So we may sleep in peace as regards future danger 
likely to come to us from comets. There is little fear 
of the destruction of humanity by these windy bags. 

These ethereal beauties whose blond locks float 
carelessly upon the azure night are not concerned with 
us; they seem to have no other preoccupation than to 

189 



ASTRONOMY FOR AMATEURS 

race from sun to sun, visiting new Heavens, indifferent 
to the astonishment they produce in us. They speed 
restlessly and tirelessly through infinity; they are the 
Amazons of space. 

What suns, w^hat v^orlds must they have visited 
since the moment of their birth! If these splendid 
fugitives could relate the story of their wanderings, 
how gladly should we listen to the enchanting descrip- 
tions of the various abodes they have journeyed to! 
But alas! these mysterious explorers are dumb; they 
tell none of their secrets, and we must needs respect 
their enigmatic silence. 

Yet, some of them have left us a modest token of 
remembrance, an almost impalpable nothing, sufficient, 
however, to enable us to address our thanks to the con- 
siderate messenger. 

Can there be any one upon the Earth who has not 
been struck by the phosphorescent lights that glide 
through the somber night, leaving a brilliant silver or 
golden track — the luminous, ephemeral trail of a meteor ^ 

Sometimes, when Nighr has silently spread the im- 
mensity of her wings above the weary Earth, a shining 
speck is seen to detach itself in the shades of evening 
from the starry vault, shooting lightly through the con- 
stellations to lose itself in the infinitude of space. 

190 



THE COMETS 

These bewitching sparks attract our eyes and 
chain our senses. Fascinating celestial fireflies, their 




Fig. 54. — A Meteor. 
191 



ASTRONOMY FOR AMATEURS 

dainty flames dart in every direction through space, 
sowing the fine dust of their gilded wings upon the fields 
of Heaven. They are born to die; their life is only a 
breath; yet the impression which they make upon the 
imagination of mortals is of the profoundest. 

The young girl dreaming in the delicious tranquillity 
of the transparent night smiles at this charming sister 
in the Heavens (Fig. 54). What can not this adorable 
star announce to the tender and loving heart ? Is it 
the shy messenger of the happiness so long desired ? 
Its unpremeditated appearance fills the soul with a ray 
of hope and makes it tremble. It is a golden beam that 
glides into the heart, expanding it in the thrills of a 
sudden and ephemeral pleasure. . . . The radiant meteor 
seems to quit the velvet of the deep blue sky to respond 
to the appeal of the imploring voice that seeks its succor. 

What secrets has it not surprised! And who bears 
malice against it ? It is the friend of the betrothed who 
invoke its passage to confide their wishes, and associate 
it with their dreams. Tradition holds that if a wish 
be formulated during the visible passage of a meteor it 
will certainly be fulfilled before the year is out. Be- 
tween ourselves, however, this is but a surviving figment 
of the ancestral imagination, for this celestial jewel takes 
no such active part in the doings of Humanity. . . . 
Besides, try to express a wish distinctly in a second! 

192 



THE COMETS 

It is a curious fact that while comets have so often 
spread terror on the Earth, shooting stars should on the 
contrary have been regarded with benevolent feelings 
at all times. And what is a shooting star ? These 
dainty excursionists from the celestial shores are not, as 
is supposed, true stars. They are atoms, nothings, 
minute fragments deriving in general from the disin- 
tegration of comets. They come to us from a vast 
distance, from millions on millions of miles, and circle 
in swarms around the Sun, following a very elongated 
ellipse which closely resembles that of the cometary orbit. 
Their flight is extremely rapid, reaching sometimes more 
than 40 kilometers (25 miles) per second, a cometary 
speed that is, as we have seen, greatly above that of our 
terrestrial vehicle, which amounts to 29 to 30 kilometers 
(about 19 miles). 

These little corpuscles are not intrinsically luminous; 
but when the orbit of a swarm of meteors crosses our 
planet, a violent shock arises, the speed of which may be 
as great as 72 kilometers (45 miles) in the first second 
if we meet the star shower directly; the average rate, 
however, does not exceed 30 to 40 kilometers (19 to 25 
miles), for these meteors nearly always cross our path 
obliquely. The height at which they arrive is usually 
no kilometers (68 miles), and 80 kilometers (50 miles) 
at the moment of disappearance of the meteor; but 

193 



ASTRONOMY FOR AMATEURS 

shooting stars have been observed at 300 kilometers 
(186 miles). 

The friction caused by chis collision high up in the 
atmosphere transforms the motion into heat. The 
molecules incandesce, and burn like true stars with a 
brilliancy that is often magnificent. 

But their glory is of short duration. The excessive 
heat resulting from the shock consumes the poor firefly; 
its remains evaporate, and drop slow^ly to the Earth, 
v^here they are deposited on the surface of the soil in a 
sort of ferruginous dust mixed with carbon and nickel. 
Some one hundred and forty-six milliards of them reach 
us annually, as seen by the unaided eye, and many more 
in the telescope; the effect of these showers of meteoric 
matter is an insensible increase in the mass of our globe, 
a slight lessening of its rotary motion, and the acceleration 
of the lunar movements of revolution. 

Although the appearance of shooting stars is a com- 
mon enough phenomenon, visible every night of the year, 
there are certain times when they arrive in swarms, 
from different quarters of the sky. The most remark- 
able dates in this connection are the night of August 
loth and the morning of November 14th. Every one 
knows the shooting stars of August loth, because they 
arrive in the fine warm summer evenings so favorable 
to general contemplation of the Heavens. The phe- 

194 



THE COMETS 

nomenon lasts till the 12th, and even beyond, but the 
maximum is on the loth. When the sky is very clear, 
and there is no moon, hundreds of shooting stars can 
be counted on those three nights, sometimes thousands. 
They all seem to come from the same quarter of the 
Heavens, which is called the radiant, and is situated 
for the August sw^arm in the constellation of Perseus, 
whence they have received the name of Perseids. Our 
forefathers also called them the tears of St. Lawrence, 
because the feast of that saint is on the same date. 
These shooting stars describe a very elongated ellipse, 
and their orbit has been identified with that of the 
Great Comet of 1862. 

The shower of incandescent asteroids on November 
14th is often much more abundant than the preceding. 
In 1799, 1833, and 1866, the meteors were so numerous 
that they were described as showers of rain, especially on 
the first two dates. For several hours the sky was fur- 
rowed with falling stars. An English mariner, Andrew 
Ellicot, who made the drawing we reproduce (Fig. 55), 
described the phenomenon as stupendous and alarming 
(November 12, 1799, 3 A. M.). The same occurred on 
November 13, 1833. The meteors that scarred the 
Heavens on that night were reckoned at 240,000, These 
shooting stars received the name of Leonids, because 
their radiant is situated in the constellation of the Lion. 
14 195 



ASTRONOMY FOR AMATEURS 



This swarm follows the same orbit as the comet of 
1866, which travels as far as Uranus, and comes back to 




Fig. 55. — ShouMng Stir^ ot \()\(.mher 12, 1799. 

From a contemporary draiving, 
196 



THE COMETS 

the vicinity of the Sun every thirty-three years. Hence 
we were entitled to expect another splendid apparition 
in 1899, but the expectations of the astronomers were 
disappointed. All the preparations for the appropriate 
reception of these celestial visitors failed to bring about 
the desired result. The notes made in observatories, 
or in balloons, admitted of the registration of only a very 
small number of meteors. The maximum was thirteen. 
During that night, some 200 shooting stars were counted. 
There were more in 1900, 1901, and, above all, in 1902. 
This swarm has become displaced. 

The night of November 27th again is visited by a 
number of shooting stars that are the disaggregated re- 
mains of the Comet of Biela. This comet, discovered 
by Biela in 1827, accomplished its revolution in six 
and a half years, and down to 1846 it responded punc- 
tually to the astronomers who expected its return as 
fixed by calculation. But on January 13, 1846, the 
celestial wanderer broke in half: each fragment went 
its own way, side by side, to return within sight from 
the Earth in 1852. It was their last appearance. 
That year the twin comets could still be seen, though 
pale and insignificant. Soon they vanished into the 
depths of night, and never appeared again. They were 
looked for in vain, and were despaired of, when on 
November 27, 1872, instead of the shattered comet, 

197 



ASTRONOMY FOR AMATEURS 

came a magnificent rain of shooting stars. They fell 
through the Heavens, numerous as the flakes of a 
shower of snow. 

The same phenomenon recurred on November 27, 
1885, and confirmed the hypothesis of the demoli- 
tion and disaggregation of Biela's Comet into shooting 
stars. 

There is an immense variety in the brilliancy of the 
shooting stars, from the weak telescopic sparks that 
vanish like a flash of lightning, to the incandescent 
bolides or fire-balls that explode in the atmosphere. 

Fig. 56 shows an example of these, and it represents 
a fire-ball observed at the Observatory of Juvisy on the 
night of August 10, 1899. It arrived from Cassiopeia, 
and burst in Cepheus. 

This phenomenon may occur by day as well as by 
night: It is often accompanied by one or several ex- 
plosions, the report of which is sometimes perceptible 
to a considerable distance, and by a shower of meteorites. 
The globe of fire bursts, and splits up into luminous frag- 
ments, scattered in all directions. The diff'erent parts of 
the fire-ball fall to the surface of the Earth, under the 
name of aerolites, or rather of uranoliths, since they 
arrive from the depths of space, and not from our 
atmosphere. 

198 



THE COMETS 

From the most ancient times we hear of showers 
of uranoliths to which popular superstitions were at- 




FiG. 56. — Fire-Ball seen from the Observatory at Juvisy, 
August 10, 1899. 

tached; and the Greeks even gave the name of Sideros 
to iron, the first iron used having been sidereal. 

199 



ASTRONOMY FOR AMATEURS 

No year passes without the announcement of several 
showers of uranoHths, and the phenomenon sometimes 




Fig. 57. — Explosion of a Fire-Bali above Madrid, 
February 10, 1896. 

causes great alarm to those who witness it. One of the 
most remarkable explosions is that which occurred above 
Madrid, February 10, 1896, a fragment from which, 

200 



THE COMETS 

sent me by M. Arcimis, Director of the Meteorological 
Institute, fell immediately in front of the National 
Museum (Fig. 57). The phenomenon occurred at 
9.30 A. M., in brilliant sunshine. The flash of the ex- 
plosion was so dazzling that it even illuminated the in- 
terior of the houses; an alarming clap of thunder was 
heard seventy seconds after, and it was believed that an 
explosion of dynamite had occurred. The fire-ball burst 
at a height of fourteen miles, and was seen as far as 
435 miles from Madrid! 

In one of Raphael's finest pictures {The Madonna of 
Foligno) a fire-ball may be seen beneath a rainbow 
(Fig. 58), the painter wishing to preserve the remem- 
brance of it, as it fell near Milan, on September 4, 151 1. 
This picture dates from 151 2. 

The dimensions of these meteorites vary consider- 
ably ; they are of all sizes, from the impalpable dust 
that floats in the air, to the enormous blocks exposed in 
the Museum of Natural History in Paris. Many of 
them weigh several million pounds. That represented 
below fell in Mexico during the shower of meteors of 
November 27, 1885. It weighed about four pounds. 

These bolides and uranoliths come to us from the 
depths of space; but they do not appear to have the same 
origin as the shooting stars. They may arise from 
worlds destroyed by explosion or shock, or even from 

201 



ASTRONOMY FOR AMATEURS 



planetary volcanoes. The lightest of them may have 
been expelled from the volcanoes of the Moon. Some 




Fig. 58.— Raphael's Fire-Bail {^The Madonna of Foligno). 
202 



THE COMETS 

of the most massive, in which iron predominates, may 
even have issued from the bowels of the Earth, projected 
into space by some volcanic explosion, at an epoch when 
our globe was perpetually convulsed by cataclysms of 
extraordinary violence. They return to us to-day after 




Fig. 59. — A Uranolith. 



being removed from the Earth to distances proportional 
to the initial speed imparted to them. This origin seems 
the more admissible as the stones that fall from the skies 
exhibit a mineral composition identical with that of the 
terrestrial materials. 

203 



ASTRONOMY FOR AMATEURS 

In any case, these uranoliths bring us back at least 
by their fall to our Earth, and from henceforward we will 
remain upon it, to study its position in space, and to take 
account of the place it fills in the Universe, and of the 
astronomical laws that govern our destiny. 



204 



CHAPTER VIII 
THE EARTH 

Our grand celestial journey lands us upon our own 
little planet, on this globe that gravitates between Mars 
and Venus (between War and Love), circulating like 
her brothers of the solar system, around the colossal 
Sun. 

The Earth! The name evokes in us the image of 
Life, and calls up the theater of our activities, our ambi- 
tions, our joys and sorrows. Does it not, in fact, to 
ignorant eyes, represent the whole of the universe ^ 

And yet, what is the Earth ^ 

The Earth is a star in the Heavens. We learned 
this much in our first lesson. It is a globe of opaque 
material, similar to the planets Mercury, Venus, Mars, 
Jupiter, etc., as previously described. Isolated on all 
sides in space, it revolves round the Sun, along a vast 
orbit that it accomplishes in a year. And while it thus 
glides along the lines of solar attraction, the terrestrial 
ball rotates rapidly upon itself in twenty-four hours. 

These statements may appear dubious at first sight, 
and contradictory to the evidence of our senses. 

205 



ASTRONOMY FOR AMATEURS 

Now that the surface of the Earth has been explored 
in all directions, there is no longer room to doubt that it 
is a globe, a sort of ball that we adhere to. A journey 
round the world is common enough to-day, and always 
yields the most complete evidence of the spherical nature 
of the Earth. On the other hand, the curvature of the 
seas is a no less certain proof. When a ship reaches the 
dark-blue line that appears to separate the sky from the 
ocean, it seems to be hanging on the horizon. Little 
by little, however, as it recedes, it drops below the hori- 
zon line; the tops of the masts being the last to disap- 
pear. The observer on board ship witnesses the same 
phenomenon. The low shores are first to disappear, 
while the high coasts and mountains are much longer 
visible. 

The aspect of the Heavens gives another proof of 
the Earth's rotundity. As one travels North or South, 
new stars rise higher and higher above the horizon in 
the one direction or the other, and those which shine in 
the latitude one is leaving, gradually disappear. If the 
surface of the Earth were flat, the ships on the sea would 
be visible as long as our sight could pierce the distance, 
and all the stars of the Heavens would be equally visible 
from the different quarters of the world. 

Lastly, during the eclipses of the Moon, the shadow 
projected by the Earth upon our satellite is always round, 

206 



THE EARTH 

This is another proof of the spherical nature of the ter- 
restrial globe. 

We described the Earth as an orb in. the Heavens, 
similar to all the other planets of the great solar family. 
We see these sister planets of our world circulating under 
the starry vault, like luminous points whose brilliancy 
is sometimes dazzling. For us they are marvelous 
celestial birds hovering in the ether, upheld by invisible 
wings. The Earth is just the same. It is supported 
by nothing. Like the soap-bubble that assumes a 
lovely iridescence in the rays of the Sun, or, better, like 
the balloon rapidly cleaving the air, it is isolated from 
every kind of support. 

Some minds have difficulty in conceiving this isola- 
tion, because they form a false notion of weight. 

The astronomers of antiquity, who divined it, knew 
not how to prevent the Earth from falling. They asked 
anxiously what the strong bands capable of holding up 
this block of no inconsiderable weight could be. At 
first they thought it floated on the waters like an island. 
Then they postulated solid pillars, or even supposed it 
might turn on pivots placed at the poles. But on what 
would all these imaginary supports have rested .? All 
these fanciful foundations of the Earth had to be given 
up, and it was recognized as a globe, isolated in every 
part. This illusion of the ancients, which still obtains 

207 



ASTRONOMY FOR AMATEURS 

for a great many citizens of our globule, arises, as we 
said, from a false conception of weight. 

Weight and attraction are one and the same force. 

A body can only fall when it is attracted, drawn by a 
more important body. Now, in whatever direction we 
may wander upon the globe, our feet are always down- 
ward. Down is therefore the center of the Earth. 

The terrestrial globe may be regarded as an im- 
mense ball of magnet, and its attraction holds us at its 
surface. We weigh toward the center. We may travel 
over this surface in all directions ; our feet will always 
be below, whatever the direction of our steps. For us^ 
'* below" is the inside of our planet, and ** above" is 
the immensity of the Heavens that extend above our 
heads, right round the globe. 

This once understood, where could the Earth fall to ? 
The question is an absurdity. ** Below" being toward 
the center, it would have to fall out of itself. 

Let us then picture the Earth as a vast sphere, de- 
tached from all that exists around it, in the infinity of 
the Heavens. A point diametrically opposed to another 
is called its antipodes. New Zealand is approximately 
the antipodes to France. Well, for the inhabitants of 
New Zealand and of France the top is reciprocally 
opposed, and the bottom, or the feet, are diametrically 
in opposition. And yet, for one as for the other, the 

208 



THE EARTH 

bottom is the soil they are held to, and the top is space 
above their heads. 

The Earth turns on itself in twenty-four hours. 
Whatever is above us, e. g., at midday, we call high; 
twelve hours later, at midnight, we give the same quali- 
fication to the part of space that w^as under our feet at 
noon. What is in the sky, and over our heads, at a given 
hour, is under our feet, and yet always in the sky, twelve 
hours later. Our position, in relation to the space that 
surrounds us, changes from hour to hour, and ^'top" 
and ''bottom" vary also, relatively to our position. 

Our planet is thus a ball, slightly flattened at the 
poles (by about 2^-2)' I^^ diameter, at the equator, is 
12,742 kilometers (7,926 miles); from one pole to the 
other is a little less, owing to the flattening of the polar 
caps. The diff'erence is some 43 kilometers (about 
27 miles). 

Its circumference is 40,000 kilometers (24,900 miles). 
This ball is surrounded by an aerial envelope, the atmos- 
phere, the height of which can not be less than 300 kilo- 
meters (186 miles), according to the observations made 
on certain shooting stars. 

We all know that this layer of air, at the bottom of 
which we live, is a beautiful azure blue that seems to 
separate us from the sidereal abyss, spreading over our 
heads in a kind of vault that is often filled with clouds, 

209 



ASTRONOMY FOR AMATEURS 

and giving the illusion of resting far off on the circle of 
the horizon. But this is only an illusion. In reality, 
there is neither vault nor horizon; space is open in all 
directions. If the atmosphere did not exist, or if it were 
completely transparent, we should see the stars by day 
as by night, for they are continually round us, at noon 
as at midnight, and we can see them in the full daylight, 
with the help of astronomical instruments. In fact, 
certain stars (the radiant Venus and the dazzling Jupi- 
ter) pierce the veil of the atmosphere, and are visible 
with the unaided eye in full daylight. 

The terrestrial surface is 510,000,000 square kilo- 
meters (200,000,000 square miles). The waters of the 
ocean cover three-quarters of this surface, /. f., 383,200,- 
000 square kilometers (150,000,000 square miles), and 
the continents only occupy 136,600,000 square kilo- 
meters (55,000 square miles)^ France represents about 
the thousandth part of the total superficies of the globe. 

Despite the asperities of mountain ranges, and the 
abysses hollowed out hv the waters, the terrestrial globe 
is fairly regular, and in relation to its volume its surface 
is smoother than that of an orange. The highest sum- 
mits of the Himalava, the profoundest depths of the 
somber ocean, do not attain to the millionth part of 
its diameter. 

In weight, the Earth is five and a half times heavier 
210 



THE EARTH 

than would be a globe of water of the same dimensions. 
That is to say: 

6,957,930,000,000,000,000,000,000 kilograms 
(6,833,000,000,000,000,000,000 tons). 

The atmospheric atmosphere with which it is sur- 
rounded represents. 

6,263,000,000,000,000,000 kilograms 
(6,151,000,000,000,000 tons). 

Each of us carries an average weight of some 17,000 
kilograms (16 tons) upon his shoulders. Perhaps some 
one will ask how it is that we are not crushed by this 
weight, which is out of all proportion with our strength, 
but to which, nevertheless, we appear insensible. It is 
because the aerial fluid enclosed within our bodies 
exerts a pressure equal and opposite to the external 
atmospheric pressure, and these pressures are at equi- 
librium. 

The Earth is characterized by no essential or par- 
ticular differences relatively to the other worlds of our 
system. Like Venus of the limpid rays, like the daz- 
zling Jupiter, like all the planets, she courses through 
space, carrying into Infinitude our hopes and destinies. 
Bigger than Mercury, Venus, and Mars, she presents a 
very modest figure in comparison with the enormous 
Jupiter, the strange system of Saturn, of Uranus, and 
even of Neptune. For us her greatest interest is that 
lo 211 



ASTRONOMY FOR AMATEURS 

she serves as our residence, and if she were not our habi- 
tation we should scarcely notice her. Dark in herself, 
she burns at a distance like a star, returning to space the 
light she receives from the Sun. At the distance of our 
satellite, she shines like an enormous moon, fourteen 
times larger and more luminous than our gentle Phoebe. 
Observed from Mercury or Venus, she embellishes the 
midnight sky with her sparkling purity as Jupiter does 
for us. Seen from Mars, she is a brilliant morning and 
evening star, presenting phases similar to those which 
Mars and Venus show from here. From Jupiter, the 
terrestrial globe is little more than an insignificant point, 
nearly always swallowed up in the solar rays. As to the 
Saturnians, Uranians, and Neptunians, if such people 
exist, they probably ignore our existence altogether. 
And in all likelihood it is the same for the rest of the 
universe. 

We must cherish no illusions as to the importance 
of our natal world. It is true that the Earth is not 
wanting in charm, with its verdant plains enameled in 
the delicious tones of a robust and varied vegetation, its 
plants and flowers, its spring-time and its birds, its lim- 
pid rivers winding through the meadow^s, its mountains 
covered with forests, its vast and profound seas ani- 
mated with an infinite variety of living creatures. The 
spectacle of Nature is magnificent, superb, admirable 

212 



THE EARTH 

and marvelous, and we imagine that this Earth fills the 
universe, and suffices for it. The Sun, the Moon, the 
stars, the boundless Heavens, seem to have been created 
for us, to charm our eyes and thoughts, to illumine our 
days, and shed a gentle radiance upon our nights. This 
is an agreeable illusion of our senses. If our Humanity 
were extinguished, the other worlds of the Heavens, 
Venus, Mars, etc., would none the less continue to gravi- 
tate in the Heavens along with our defunct planet, and 
the close of human life (for which everything seems to us 
to have been created) would not even be perceived by 
those other worlds, that nevertheless are our neighbors. 
There would be no revolution, no cataclysm. The 
stars would go on shining in the firmament, just as they 
do to-day, shedding their divine light over the immensity 
of the Heavens. Nothing would be changed in the 
general aspect of the Universe. The Earth is only a 
modest atom, lost in the innumerable army of the worlds 
and suns that people the universe. 

Every morning the Sun rises in the East, setting fire 
with his ardent rays to the sky, which is dazzling with 
his splendor. He ascends through space, reaches a cul- 
minating point at noon, and then descends toward the 
West, to sink at night into the purple of the sunset. 

And then the stars, grand lighthouses of the Heavens, 
213 



ASTRONOMY FOR AMATEURS 

in their turn incandesce. They too rise in the East, 
ascend the vault of Heaven, and then descend to the 
West, and vanish. All the orbs, Sun, Moon, planets, 
stars, appear to revolve round us in twenty-four 
hours. 

This journey of the orbs around us is only an illu- 
sion of the senses. 

Whether the Earth be at rest, and the sky animated 
with a rotary movement round her, or v^hether, on the 
conjtrary, the stars are fixed, and the Earth in motion, 
in either case, for us appearances are the same. If the 
Earth turns, carrying all that pertains to it in its motion 
— the seas, the atmosphere, the clouds, and ourselves, — 
we are unable to perceive it, because all the objects that 
surround us keep their respective positions among them- 
selves. Hence we must resort to logic, and reason out 
the two hypotheses. 

For the accomplishment of this rapid journey of the 
Sun and stars around the Earth, it would be necessary 
that all the orbs of the sky should be in some way at- 
tached to a vault, or to circles, as was formerly supposed. 
This conception is childish. The peoples of antiquity 
had no notion of the size of the universe, and their error 
is almost excusable. The distance separating Heaven 
from the Infernal Regions has been measured, according 
to Hesiod, by Vulcan's anvil, which fell from the skies 

214 



THE EARTH 

to the Earth in nine days and nine nights, and it would 
have taken as long again to continue its journey from 
the surface of the Earth to the bowels of Hades. 

To-day we have a more exact notion of the grandeur 
of the Universe. We know that millions and trillions of 
miles separate the stars from one another. And by 
representing these distances, we can form some idea of 
the difficulty there would be in admitting the rotation 
of the universe round the Earth. 

The distance from here to the Sun is 149,000,000 
kilometers (93,000,000 miles). In order to turn in 
twenty-four hours round the Earth, that orb would have 
to fly through Space at a velocity of more than 10,000 
kilometers (6,200 miles) a second. 

Yes! the Sun, splendid orb, source of our existence 
and of that of all the planets, a colossal globe, over a 
million times more voluminous than the Earth, and 
324 thousand times heavier, would have to accomplish 
this immense revolution in order to turn round the 
minute point that is our lilliputian world! 

This in itself would suffice to convince us of the want 
of logic in such an argument. But the Sun is not alone 
in the Heavens. We should have to suppose that all 
the planets and all the stars were engaged in the same 
fantastic motions. 

Jupiter is about five times as far off as the Sun; his 

215 



ASTRONOMY FOR AMATEURS 

velocity would have to be 53,000 kilometers (32,860 
miles) per second. 

Neptune, thirty times farther off, would have to 
execute 320,000 kilometers (198,000 miles) per second. 

The nearest star, a of the Centaur, situated at a 
distance 275,000 times that of the Sun, would have to 
run, to fly through space, at a rate of 2,941,000,000 
kilometers (1,823,420,000 miles) per second. 

All the other stars are incomparably farther off, at 
infinity. 

And this fantastic rotation would all be accom- 
pKshed round a minute point! 

To put the problem in this way is to solve it. Unless 
we deny the astronomic measures, and the most convin- 
cing geometric operations, the Earth's diurnal motion 
of rotation is a certainty. 

To suppose that the stars revolve round the Earth 
is to suppose, as one author humorously suggests, that 
in order to roast a pheasant the chimney, the kitchen, 
the house, and all the countryside must needs turn 
round it. 

If the Earth turns in twenty-four hours upon itself, 
a point upon the equator would simply travel at a rate of 
465 meters (1,525 feet) per second. This speed, while 
considerable in comparison with the movements observed 
upon the surface of our planet, is as nothing compared 

216 



THE EARTH 

with the fantastic rapidity at which the Sun and stars 
would have to move, in order to rotate round our globe. 

Thus we have to choose between these two hypo- 
theses: either to make the entire Heavens turn round us 
in twenty-four hours, or to suppose our globe to be ani- 
mated by a motion of rotation upon itself. For us, the 
impression is the same, and as we are insensible to the 
motion of the Earth, its immobility w^ould seem almost 
natural to us. So that, in last resort, here as in many 
other instances, the decision must be made by simple 
common sense. Science long ago made its choice. 
Moreover, all the progress of Astronomy has confirmed 
the rotary movement of the Earth in twenty-four hours, 
and its movement of revolution round the Sun in a year; 
while at the same time a great number of other mo- 
tions have been discovered for our wandering planet. 

The learned philosophers of antiquity divined the - 
double movement of our planet. The disciples of Py- 
thagoras taught it more than two thousand years ago, 
and the ancient authors quote among others Nicetas of 
Syracuse, and Aristarchus of Samos, as being among the 
first to promote the doctrine of the Earth's movement. 
But at that remote period no one had any idea of the 
real distances of the stars, and the argument did not 
seem to be based on any adequate evidence. Ptolemy, 
after a long discussion of the diurnal motion of our 

217 



ASTRONOMY FOR AMATEURS 

planet, refutes it, giving as his principal reason that 
if the Earth turned, the objects that were not fixed to its 
surface would appear to move in a contrary direction, 
and that a body shot into the air would fall back to the 
West of its starting-point, the Earth having turned mean- 
time from West to East. This objection has no weight, 
because the Earth controls not only all the objects fixed 
to the soil, but also the atmosphere, and the clouds that 
surround it like a light veil, and all that exists upon its 
surface. The atmosphere, the clouds, the waters of the 
ocean, things and beings, all are adherent to it and make 
one body with it, participating in its movement, as 
sometimes happens to ourselves in the compartment of a 
train, or the car of an aerostat. When, for instance, we 
drop an object out of such a car, this object, animated 
with the acquired velocity, does not fall to a point below 
the aerostat, but follows the balloon, as though it were 
gliding along a thread. The author has made this ex- 
periment more than once in aerial journeys. 

Thus, the hypothesis of the Earth's motion has be- 
come a certainty. But in addition to reasoning, direct 
proof is not wanting. 

I, The spheroidal shape of the Earth, slightly flat- 
tened at the poles and swollen at the equator, has been 
produced by the rotary motion, by the centrifugal force 
that it engenderSc 

2l8 



THE EARTH 

2. In virtue of this centrifugal force, which is at its 
maximum at the equator, objects lose a little of their 
weight in proportion as they are farther removed from 
the polar regions where centrifugal force is almost nil. 

3. In virtue of this same centrifugal force, the length 
of the pendulum in seconds is shorter at the equator than 
in Paris, and the difference is one of 3 millimeters. 

4. A weight abandoned to itself and falling from a 
certain height, should follow the vertical if the Earth 
were motionless. Experiment, frequently repeated, 
shows a slight deviation to the East, of the plumb-line 
that marks the vertical. We more especially observed 
this at the Pantheon during the recent experiments. 

5. The magnificent experiment of Foucault at the 
Pantheon, just renewed under the auspices of the As- 
tronomical Society of France, demonstrates the rotary 
motion of the Earth to all beholders. A sufficiently 
heavy ball (28 kilograms, about 60 pounds) is suspended 
from the dome of the edifice by an excessively fine steel 
thread. When the pendulum is in motion, a point at- 
tached to the bottom of the ball marks its passage 
upon two little heaps of sand arranged some yards 
away from the center. At each oscillation this point 
cuts the sand, and the furrow gets gradually longer to 
the right hand of an observer placed at the center of 
the pendulum. The plane of the oscillations remains 

219 



ASTRONOMY FOR AMATEURS 

fixed; but the Earth revolves beneath, from West to 
East. The fundamental principle of this experiment is 
that the plane in w^hich any pendulum is made to oscil- 
late remains invariable even when the point of suspen- 
sion is turned. This demonstration enables us in some 
measure to see the Earth turning under our feet. 

The annual displacements of the stars are again con- 
firmatory of the Earth's motion round the Sun. During 
the course of the year, the stars that are least remote 
from our solar province appear to describe minute 
ellipses, in perspective, in the Heavens. These small 
apparent variations in the position of the nearest stars 
reproduce the annual rotation of the Earth round the 
Sun, in perspective. 

We could adduce further observations in favor of 
this double movement, but the proofs just given are 
sufficiently convincing to leave no doubt in the mind of 
the reader. 

Nor are these two the only motions by which our 
globe is rocked in space. To its diurnal rotation and 
its annual rotation we may add another series of ten 
more motions', some very slow, fulfilling themselves in 
thousands of years, others, more rapid, being constantly 
renewed. It is, however, impossible in these restricted 
pages to enter into the detail reserved for more complete 
works. We must not forget that our present aim is to 

220 



THE EARTH 

sum up the essentials of astronomical knowledge as 
simply as possible, and to offer our readers only the 
**best of the picking." 

The two principal motions of which we have just 
spoken give us the measure of time, the day of twenty- 
four hours, and the year of 365 J days. 

The Earth turning upon itself in twenty-four hours 
from West to East, presents all its parts in succession to 
the Sun fixed in space. Illuminated countries have the 
day, those opposite, in the shadow of the Earth, are 
plunged into night. The countries carried by the Earth 
toward the Sun have morning, those borne toward his 
shadow, evening. Those which receive the rays of the 
day-star directly have noon; those which are just op- 
posite have midnight. 

The rotation of our planet in this way gives us the 
measure of time; it has been divided arbitrarily into 
twenty-four periods called hours; each hour into sixty 
minutes; each minute into sixty seconds. 

In consequence, each country turns in twenty-four 
hours round the axis of the Earth. The difference in 
hours between the different regions of the globe is there- 
fore regulated by the difference of geographical position. 
The countries situated to the West are behind us; the 
Sun only gets there after it has shone upon our meridian, 

221 



ASTRONOMY FOR AMATEURS 

When it is midday in Paris, it is only 11.51 A. m. in 
London; 11.36 a. m. in Madrid; 11. 14 a. m. at Lisbon; 



Fig. 60. — Motion of the Earth round the Sun. 

1 1. 12 A. M. at Mogador; 7.06 a. m. at Quebec; 6.55 a. m. 
at New York; 5.14 a. m. in Mexico; and so on. The 
countries situated to the East are, on the contrary, ahead 

222 



THE EARTH 

of us. When it is noon in Paris, it is already 56 
minutes after midday at Vienna; 1.25 P. M. at Athens; 
2.21 P. M. at Moscow; 3.16 p.m. at Teheran; 4.42 P. M. 
at Bombay; and so on. We are here speaking of real 
times, and not of the conventional times. 

If we could make the tour of the world in twenty-four 
hours, starting at midday from some place to go round 
the globe, and traveling westward with the Sun, we 
should have him always over our heads. In traveling 
round the world from West to East, one goes in front of 
the Sun, and gains by one day; in taking the opposite 
direction, from East to West, one loses a day. 

In reality, the exact duration of the Earth's diurnal 
rotation is twenty-three hours, fifty-six minutes, four sec- 
onds. That is the sidereal day. But, while turning upon 
itself, the Earth circulates upon its orbit, and at the 
end of a diurnal rotation it is still obliged to turn during 
three minutes, fifty-six seconds in order to present ex- 
actly the same meridian to the fixed Sun which, in con- 
sequence of the rotary period of our planet, is a little 
behind. The solar day is thus one of twenty-four hours. 
There are 366 rotations in the year. 

And now let us come back to the consequences of 
the Earth's motion. In the first place our planet does 
not turn vertically nor on its side, but is tipped or in- 
clined a certain quantity: 23° 27^ 

223 



ASTRONOMY FOR AMATEURS 

Now, throughout its annual journey round the Sun, 
the incKnation remains the same. That is what pro- 
duces the seasons and dimates. The countries which 
have a larger circle to travel over in the hemisphere of 
the solar illumination have the longer days, those which 
have a smaller circle, shorter days. At the equator 
there is constantly, and all through the year, a twelve- 
hour day, and a night of twelve hours. 




<r 



Fig. 6i. — Inclination of the Earth. 

In summer, the pole dips toward the Sun, and the 
rays of the orb of day cover the corresponding hemi- 
sphere with their light. Six months later this same 
hemisphere is in winter, and the opposite hemisphere 
is in its turn presented to the Sun. June 21 is the 
summer solstice for the northern hemisphere, and is at 
the same time winter for the southern pole. Six months 
later, on December 21, we have winter, while the south- 

224 



THE EARTH 

ern hemisphere is completely exposed to the Sun. Be- 
tween these two epochs, w^hen the radiant orb shines 
exactly upon the equator, that is on March 21, w^e 
have the spring equinox, that delicious flowering season 
when all nature is enchanting and enchanted; on Sep- 
tember 21 we have the autumn equinox, melancholy, 
but not devoid of charm. 

The terrestrial sphere has been divided into different 
zones, with which the different climates are in relation: 

1. The tropical zone, which extends 23° 27' from 
one part to the other of the equator. This is the hottest 
regionc It is limited by the circle of the tropics. 

2. The temperate zones, which extend from 23° 27' 
to 66° 23' of latitude, and where the Sun sets every day. 

3. The glacial zones, drawm round the poles, at 
66° 33' latitude, w^here the Sun remains constantly above 
or below the horizon for several days, or even several 
months. These glacial zones are limited by the polar 
circles. 

We must add that the axis of the Earth is a straight 
line that is supposed to pass through the center of the 
globe and come out at two diametrically opposite points 
called the poles. The diurnal rotation of the Earth is 
effected round this axis. 

The name equator is given to a great circle situated 
between the two poles, at equal distance, which divides 

225 



ASTRONOMY FOR AMATEURS 



the globe into two hemispheres. The equator is 
divided into 360 parts or degrees, by other circles that 
go from one pole to the other. These are the longitudes 
or meridians (see Fig. 62). The distance between the 
equator and the pole is divided into larger or smaller 
circles, which have received the name of latitudes. 

90 degrees are reck- 
oned on the one side 
and the other of the 
equator, in the di- 
rection of the North 
and South poles, 
respectively. The 
longitudes are reck- 
oned from some 
point either to East 
or West: the lati- 
tudes are reckoned 
North and South, 
from the equator. 
In going from East to West, or inversely, the longitude 
changes, but in passing from north to South of any 
spot, it is the latitude that alters. 

The circles of latitude are smaller in proportion as 
one approaches the poles. The circumference of the 
world is 40,076,600 meters at the equator. At the 

226 




Fig. 62. — The divisions of the globe. 
Longitudes and latitudes. 



THE EARTH 

latitude of Paris (48^ 50') it is only 26,431,900 meters. 
A point situated at the equator has more ground to 
travel over in order to accomplish its rotation in tv^enty- 
four hours than a point nearer the pole. 

We have already stated that this velocity of rotation 
is 465 meters per second at the equator. At the latitude 
of Paris it is not more than 305 meters. At the poles 
it is nil. 

The longitudes, or meridians, are great circles of 
equal length, dividing the Earth into quarters, like the 
parts of an orange or a melon. These circumvent the 
globe, and measure some 40,000,000 (40,008,032) meters. 
We may remember in passing that the length of the 
meter has been determined as, by definition, the ten- 
millionth part of the quarter of a celestial meridian. 

Thus, w^hile rotating upon itself, the Earth spins 
round the Sun, along a vast orbit traced at 149,000,000 
kilometers (93,000,000 miles) from the central focus, a 
sensibly elliptical orbit, as v^e have already pointed out. 
It is a little nearer the Sun on January ist than on July 
1st, at its perihelion {peri, near, helios, Sun), than at 
its aphelion {apo, far, helios, Sun). The difference = 
6,000,000 kilometers (3,720,000 miles), and its velocity 
is a little greater at perihelion than at aphelion. 

This second motion produces the year. It is accom- 
plished in three hundred and sixty-five days, six hours, 
16 227 



ASTRONOMY FOR AMATEURS 

nine minutes, nine seconds. Such is the complete 
revolution of our planet round the orb of day. It has 
received the name of sidereal year. But this is not how 
we calculate the year in practical life. The civil year, 
known also as the tropical year, is not equivalent to 
the Earth's revolution, because a very slow gyratory 
motion, called *'the precession of the equinoxes," 
the cycle of which occupies 25,765 years, drags the 
spring equinox back some twenty minutes in each 
year. 

The civil year is, accordingly, three hundred and 
sixty-five days, five hours, forty-eight minutes, forty-six 
seconds. 

In order to simplify the calendar, this accumulating 
fraction of five hours, forty-eight minutes, forty-six 
seconds (about a quarter day) is added every four years 
to a bissextile year (leap-year), and thus we have uneven 
years of three hundred and sixty-five, and three hundred 
and sixty-six days. Every year of which the figure is 
divisible by four is a leap-year. By adding a quarter day 
to each year, there is a surplus of eleven minutes, fourteen 
seconds. These are subtracted every hundred years by 
not taking as bissextile those secular years of which the 
radical is not divisible by four. The year 1600 was leap- 
year: 1700, 1800, and 1900 were not; 2000 will be. The 
agreement between the calendar and nature has thus 

228 



THE EARTH 

been fairly perfect, since the establishment of the Gre- 
gorian Calendar in 1582. 

Since the terrestrial orbit measures not less than 
930,000,000 kilometers (576,600,000 miles), which must 
be traversed in a year, the Earth flies through Space at 
2,544,000 kilometers (1,577,280 miles) a day, or 106,000 
kilometers (65,720 miles) an hour, or 29,500 meters 
(18 miles) per second on an average, a little faster at 
perihelion, a little slower at aphelion. This giddy 
course, a thousand times more rapid than the speed of 
an express-train, is effected without commotion, shock, 
or noise. Reasoning alone enables us to divine the 
prodigious movement that carries us along in the vast 
fields of the Infinite, in mid-heaven. 

Returning to the calendar, it must be remarked in 
conclusion, that the human race has not exhibited great 
sense in fixing the New Year on January i. No more dis- 
agreeable season could have been selected. And further, 
as the ancient Roman names of the months have been 
preserved, which in the time of Romulus began with 
March, the '' seventh " month, ''September," is our 
ninth month; October (the eighth) is the tenth; Novem- 
ber (the ninth) has become the eleventh; and December 
(the tenth) has taken the place of the twelfth. Verily, 
we are not hard to please! 

These months, again, are unequal, as every one 
229 



ASTRONOMY FOR AMATEURS 



knows. Witness the simple expedient of remembering 
the long and short months, by closing the left hand and 
counting the knobs and hollows of the fist, the former 
corresponding to the long months, the latter to the short: 





I JANUARY 31 Days 

^ FEBRUARY as^-ag 

I MARCH 31 

APRIL 30 

J MAY 31 

'JUNE 30 

JULY 31 



>. 



/ 



AUGUST 31 

SEPTEMBER 30 

OCTOBER 31 
NOVEMBER 30 

DECEMBER 31 



Fig. 63. — To find the 
long and short months. 



first knob = January; first hollow, February; second 
knob, March; and so on."^ 

* Translator : Compare the well-known English rhyme : 
Thirty days hath September, 
April, June, and November. 
While all the rest have thirty-one, 
Excepting February alone, 

In which but twenty-eight appear • 

And twenty-nine when comes Leap Year 

230 



THE EARTH 

Should not the real renewal of the year coincide with 
the awakening of Nature, with the spring on the terres- 
trial hemisphere occupied by the greater portion of Hu- 
manity, with the date of March 2ist? Should not the 
months be equalized, and their names modified ? Why 
should we not follow the beautiful evolution dictated 
by the Sun and by the movement of our planet ? But 
our poor Earth may roll on a long time yet before its 
inhabitants will become reasonable. 



231 



CHAPTER IX 
THE MOON 

It is the delightful hour when all Nature pauses in 
the tranquil calm of the silent night. 

The Sun has cast his farewell gleams upon the weary 
Earth. All sound is hushed. And soon the stars will 
shine out one by one in the bosom of the somber firma- 
ment. Opposite to the sunset, in the east, the Full 
Moon rises slowly, as it were calling our thoughts toward 
the mysteries of eternity, while her limpid night spreads 
over space like a dew from Heaven. 

In the odorous woods, the trees are silhouetted 
strangely upon the sky, seeming to stretch their knotted 
arms toward this celestial beauty. On the river, smooth 
as a mirror, w^herein the pale Phoebe reflects her splen- 
dor, the maidens go to seek the floating image of their 
future spouse. And in response to their prayers, she 
rends the veil of cloud that hides her from their eyes, 
and pours the reflection of her gentle beams upon the 
sleeping waters. 

From all time the Moon has had the privilege of 
232 



THE MOON 

charming the gaze, and attracting the particular attention 
of mortals. What thoughts have not been wafted to her 
pale, yet luminous disk ? Orb of mystery and of soli- 
tude, brooding over our silent nights, this celestial lumi- 
nary is at once sad and splendid in her glacial purity, 
and her limpid rays provoke a reverie full of charm 
and melancholy. Mute w^itness of terrestrial destinies, 
her nocturnal flame w^atches over our planet, follovv^ing 
it in its course as a faithful satellite. 

The human eye first uplifted to the Heavens was 
struck, above all, with the brilliancy of this solitary globe, 
straying among the stars. The Moon first suggested 
an easy division of time into months and weeks, and 
the first astronomical observations were limited to the 
study of her phases. 

Daughter of the Earth, the Moon was born at the 
limits of the terrestrial nebula, when our world was still 
no more than a vast gaseous sphere, and was detached 
from her at some critical period of colossal solar tide. 
Separating with regret from her cradle, but attached to 
the Earth by indissoluble ties of attraction, she rotates 
round us in a month, from west to east, and this move- 
ment keeps her back a little each day in relation to the 
stars. If we watch, evening by evening, beginning from 
the new moon, we shall observe that she is each night 
a little farther to the left, or east, than on the preceding 

233 



ASTRONOMY FOR AMATEURS 

evening. This revolution of the Moon around our 
planet produces the phases, and gives the measure of 
our months. 




Fig. 64. — The Full Moon slowly rises, 
234 



THE MOON 

During her monthly journey she always presents 
the same face to us. One might think that the fear of 
losing us had immobilized her globe, and prevented her 
from turning. And so we only know of her the vague 
sketch of a human face that has been observed through 
all the ages. 

It seems, in fact, as though she were looking down 
upon us from the Heavens, the more so as the principal 
spots of her disk vaguely recall the aspect of a face. If 
we try to draw it without the aid of instruments we 
observe dark regions and clear regions that each inter- 
prets in his own fashion. To the author, for instance, 
the full Moon has the appearance represented in the 
following figure. The spots resemble two eyes and the 
sketch of a nose; resulting in a vague human figure, 
as indicated on the lower disk. Others see a man car- 
rying a bundle of wood, a hare, a lion, a dog, a kan- 
garoo, a sickle, two heads embracing, etc.* But gen- 
erally speaking, there is a tendency to see a human 
figure in it. 

If this appearance is helped a little by drawing, it 
gives the profile of a man's head fairly well sketched, 
and furnished with an abundant crop of hair (Fig. 66). 

* Fifty-eight different pictures of the aspect of the Moon to the unaided 
eye will be found in the Monthly Bulletins of the Astronomical Society of 
France, for the year 1900, in pursuance of an investigation made by the 
author among the different members of the Society. 

235 



ASTRONOMY FOR AMATEURS 

Others go much more into detail, and draw a woman's 
head that is certainly too definite, Uke this of M. Jean 




Fig. 65. — The Moon viewed with the unaided eye. 

Sardou (Fig. 67). Others, again, Hke M. Zamboni, 
see behind the man's profile the likeness of a young girl 

236 



THE MOON 

being embraced by him (Fig. 68). There is certainly 
some imagination about these. And yet, on the first 
suitable occasion, look at the Moon through an opera- 
glass, a few days after the first quarter, and you will 




Fig. 66. — The Man's head in the Moono 

not fail to see the masculine profile just described, and 
even to imagine the **kiss in the Moon.'' 

These vague aspects disappear as soon as the Moon 
is examined with even the least powerful instruments: 



ASTRONOMY FOR AMATEURS 



the spots are better defined, and the illusions of indistinct 
vision vanish. Compare this direct photograph of the 
Moon, taken by the author some years ago (Fig. 69): 
here is neither a human figure, man, dog, hare, nor 
faggot; simply deep geographical configurations, and in 
the low^er region, a luminous point v^hence certain light 




Fig. 67. — Woman's head in the Moon. 

bands spread out, some being prolonged to a consider- 
able distance. And yet, from a little v^ay off, does it 
not form the man's face above indicated ^ 

From the earliest astronomical observations made 
with the aid of instruments by GaHleo, in 1609, people 
tried to find out what the dark spots could represent, 

238 



THE MOON 

and they were called seas, because water absorbs light, 
and reflects it less than terra firma. The Moon of itself 




Fig. 68. — The kiss in the Moon. 

239 



ASTRONOMY FOR AMATEURS 

possesses no intrinsic light, any more than our planet, 
and only shines by the light of the Sun that illuminates 
it. As it rotates round the Earth, and constantly 
changes its position with respect to the Sun, we see more 



'^:. 



Fig. 69. — Photograph of the Moon. 



or less of its illuminated hemisphere, and the result is 
the phases that every one knows so well. 

At the commencement of each lunation, the Moon is 
between the Sun and the Earth, and its non-illuminated 
hemisphere is turned toward us. This is the New 

240 



THE MOON 

Moon, invisible to us; but two days later, the slim cres- 
cent of Diana sheds a gentle radiance upon the Earth. 
Gradually the crescent enlarges. When the Moon ar- 
rives at right angles w^ith ourselves and v^ith the Sun, 
half the illuminated hemisphere is presented to us. 
This is the first quarter. At the time of Full Moon, it is 
opposite the Sun, and v^e see the whole of the hemisphere 

9 
> 



Suns 



^ 



R 



ays. 



-> 




c 

Fig. 70. — The Moon's Phases. 

illuminated. Then comes the decline: the brilliant disk 
is slightly corroded at first; it diminishes from day to day, 
and about a week before the New Moon our fair friend 
only shows her profile before she once more passes in 
front of the Sun: this is the last quarter. 

When the Moon is crescent, in the first evenings of 
the lunation, and after the last quarter, the rest of the 

241 



ASTRONOMY FOR AMATEURS 

disk is visible, illuminated feebly by a pale luminosity. 
This is known as the ashy light. It is due to the shine 
of the Earth, reflecting the light received from the Sun 
into space. Accordingly the ashy light is the reflection 
of our ov^n sent back to us by the Moon. It is the reflec- 
tion of a reflection. 

This rotation of the Moon round the Earth is accom- 
plished in twenty-seven days, seven hours, forty-three 
minutes, eleven seconds; but as the Earth is simulta- 
neously revolving round the Sun, when the Moon returns 
to the same point (the Earth having become displaced 
relatively to the Sun), the Moon has to travel two days 
longer to recover its position between the Sun and the 
Earth, so that the lunar month is longer than the sidereal 
revolution of the Moon, and takes twenty-nine days, 
twelve hours, forty-four minutes, three seconds. This 
is the duration of the sequence of phases. 

This revolution is accomplished at a distance of 
384,000 kilometers (238,000 miles). The velocity of 
the Moon in its orbit is more than i kilometer (0.6214 
mile) per second. But our planet sweeps it through 
space at a velocity almost thirty times greater. 

The diameter of the Moon represents ^^Vo^ ^^^^ ^f 
the Earth, /. ^., 3,480 kilometers (2,157 miles). 

Its surface = 38,000,000 square kilometers 
(15,000,000 square miles), a little more than the thir- 

242 



THE MOON 

teenth part of the terrestrial surface, which = 510,000,000 
(200,000^000 square miles). 

In volume, the Moon is fifty times less than the 
Earth. Its mass or weight is only -^ that of the ter- 
restrial globe. Its density = 0.615, relatively to that 
of the Earth, /. e., a little more than three times that of 
water. Weight at its surface is very little: 0.174. A 
kilogram transported thither would only weigh 174 
grams. 

At the meager distance of 384,000 kilometers 
(238,000 miles) that separates us from it (about thirty 
times the diameter of the Earth), the Moon is a suburb 
of our terrestrial habitation. What does this small dis- 
tance amount to ? It is a mere step in the universe. 

A telegraphic message would get there in one and 
a half second; a projectile fired from a gun would arrive 
in eight days, five hours; an express-train would be due 
in eight months, twenty-two days. It is only the 3^ 
part of the distance that separates us from the Sun, 
and only the to^^^oT P^^^ ^^ ^^^ distance of the stars 
nearest to us. Many men have tramped the distance 
that separates us from the Moon. A bridge of thirty 
terrestrial globes would suffice to unite the two worlds. 

Owing to this great proximity, the Moon is the best 
known of all the celestial spheres. Its geographical 
17 243 



ASTRONOMY FOR AMATEURS 

(or more correctly, selenographical, Selene, moon) map 
was drawn out more than two centuries ago, at first in a 
vague sketch, and afterward with more details, until 
to-day it is as precise and accurate as any of our ter- 
restrial maps of geography. 

Before the invention of the telescope, from antiquity 
to the seventeenth century, people lost themselves in 
conjectures as to the nature of this strange lunar figure. 
It was held to be a mysterious world, the more extraor- 
dinary in that it always presented the same face to us. 
Some compared it to an immense mirror reflecting the 
image of the Earth. Others pictured it as a silver star, 
an enchanted abode where all was wealth and happiness. 
For many a long day it was the fashion to think, quite 
irrationally, that the inhabitants of the Moon were 
fifteen times bigger than ourselves. 

The invention of telescopes, however, brought a 
little order and a grain of truth into these fantastic 
assumptions. The first observations of Galileo revo- 
lutionized science, and his discoveries filled the best- 
ordered minds with enthusiasm. Thenceforward, the 
Moon became our property, a terrestrial suburb, where 
the whole world would gladly have installed itself, had 
the means of getting there been as swift as the wings of 
the imagination. It became easy enough to invent a 
thousand enchanting descriptions of the charms of our 

244 



THE MOON 

fair sister, and no one scrupled to do so. Soon, it was 
observed that the Moon closely resembled the Earth in 
its geological features; its surface bristles with sharp 
mountain peaks that light up in so many luminous 
points beneath the rays of the Sun. Alongside, dark 
and shaded parts indicate the plains; moreover, there 
are large gray patches that were supposed to be seas 
because they reflect the solar light less perfectly than 
the adjacent countries. At that epoch hardly anything 
was known of the physical constitution of the Moon, 
and it was figured as enveloped with an atmospheric 
layer, analogous to that at the bottom of which we carry 
on our respiration. 

To-day we know that these ''seas" are destitute of 
water, and that if the lunar glebe possesses an atmos- 
phere, it must be excessively light. 

The Moon became the favorite object of astrono- 
mers, and the numerous observations made of it author- 
ized the delineation of very interesting selenographic 
charts. In order to find one's way among the seas, 
plains, and mountains that make up the lunar territory, 
it was necessary to name them. The seas were the first 
to be baptized, in accordance with their reputed astro- 
logical influences. Accordingly, we find on the Moon, 
the Sea of Fecundity, the Lake of Death, the Sea of 
Humors, the Ocean of Tempests, the Sea of Tranquillity, 

245 



ASTRONOMY FOR AMATEURS 

the Marsh of Mists, the Lake of Dreams, the Sea of 
Putrefaction, the Peninsula of Reverie, the Sea of 
Rains, etc. 

With regard to the luminous parts and the mountains, 
it was at first proposed to call them after the most illus- 
trious astronomers, but the fear of giving oflFense acted 
as a check on Hevelius and Riccioli, authors of the first 
lunar maps (1647, ^651), and they judged it more 
prudent to transfer the names of the terrestrial moun- 
tains to the Moon. The Alps, the Apennines, the Pyre- 
nees, the Carpathians, are all to be found up there; then, 
as the vocabulary of the mountains was not adequate, 
the scientists reasserted their rights, and we meet in the 
Moon, Aristotle, Plato, Hipparchus, Ptolemy, Coper- 
nicus, Kepler, Newton, as well as other more modern 
and even contemporaneous celebrities. 

We have not space to reproduce the general chart 
of the Moon (that published by the author measures not 
less than a meter, with the nomenclature); but the figure 
subjoined gives a summary sufficient for the limits of 
this little book. Here are the names of the principal 
lunar mountains, with the numbers corresponding to 
them upon the map. 

The constantly growing progress of optics leads to 
perpetual new discoveries in science, and at the present 
time we can say that we know the geography of the Moon 

246 



w 



i 










r ^^ 






-- -1^ ^^^ 



VN, 




.'^5 H 






"^^ 



- (I 



'if' 






' -^=.' :^^- 



■L .- 



--^^^ 







Fig 


• / 


I.— 


-Map of the 


Moon 








(From 


Fowl 


er's 


"Telescopic A 


stronomy.") 




I 


Furnerius 






14 


Albategnius 






27 


Arzachel 


2 


Petavius 






15 


Hipparchus 






28 


Walter 


3 


Langrenus 






16 


Manilius 






29 


Clavius 


4 


Alacrobius 






17 


Eudoxus 






30 


Tycho 


5 


Cleomedes 






18 


Aristotle 






31 


Bullialdus 


6 


Endymion 






'9 


Cassini 






32 


Schiller 


7 


Altas 






20 


Aristillus 






33 


Schickard 


8 


Hercules 






21 


Plato 






34 


Gassendi 


9 


Romer 






22 


Archimedes 






35 


Kepler 


lO 


Posidonius 






23 


Eratosthenes 






36 


Grimaldi 


II 


Fracastorius 






^4 


Copernicus 






37 


Aristarchus 


12 


Theophilus 






-5 


Ptolemy 










13 


Piccolomini 
Mare Crisum 




F 


26 


Alphonsus 




V 


Altai 




A 


Mare Imbrium 


Mountains 


B 


" Fercunditatis 


G 


Sinus Iridum 


i 


W 


Mare 


V aporum 


C 


" Nectaris 




H 


Oceanus Procellarum [ 


X 


Apennine Mountains 


D 


'* Tranquilitatis 


I 


Mare Humorum 




Y 


Caucasus " 


E 


" Serenitatis 




K 


' 


Nubium 




Z 


Alps 





247 



ASTRONOMY FOR AMATEURS 

as well as, and even better than, that of our own planet. 
The heights of all the mountains of the Moon are meas- 
ured to within a few feet. (One cannot say as much 
for the mountains of the Earth.) The highest are over 
7,000 meters (nearly 25,000 feet). Relatively to its 
proportions, the satellite is much more mountainous 
than the planet, and the plutonian giants are much more 
numerous there than here. If we have peaks, like 
the Gaorisankar, the highest of the Himalayas and 
of the whole Earth, whose elevation of 8,840 meters 
(29,000 feet) is equivalent to xiVo" ^^^ diameter of 
our globe, there are peaks on the Moon of 7,700 
meters (25,264 feet), e. ^., those of Doerfel and Leibniz, 
the height of which is equivalent to :^^q- the lunar di- 
ameter. 

Tycho's Mountain is one of the finest upon our 
satellite. It is visible with the naked eye (and perfectly 
with opera-glasses) as a white point shining like a kind 
of star upon the lower portion of the disk. At the time 
of full moon it is dazzling, and projects long rays from 
afar upon the lunar globe. So, too. Mount Coper- 
nicus, whose brilliant whiteness sparkles in space. But 
the strangest thing about these lunar mountains is that 
they are all hollow, and can be measured as well in depth 
as in height. A type of mountain as strange to us as 
are the seas without water! In effect, these mountains 

248 



THE MOON 

of the moon are ancient volcanic craters, with no sum- 
mits, nor covers. 

At the top of the highest peaks, there is a large cir- 
cular depression, prolonged into the heart of the moun- 
tain, sometimes far below the level of the surrounding 
plains, and as these craters often measure several hun- 
dred kilometers, one is obliged, if one does not want to 
go all round them in crossing the mountain, to descend 
almost perpendicularly into the depths and cross there, 
to reascend the opposite side, and return to the plain. 
These alpine excursions incontestably deserve the name 
of perilous ascents! 

No country on the Earth can give us any notion of 
the state of the lunar soil: never was ground so tor- 
mented; never globe so profoundly shattered to its very 
bowels. The mountains are accumulations of enormous 
rocks tumbled one upon the other, and round the awful 
labyrinth of craters one sees nothing but dismantled 
ramparts, or columns of pointed rocks like cathedral 
spires issuing from the chaos. 

As we said, there is no atmosphere, or at least so 
little at the bottom of the valleys that it is imperceptible. 
No clouds, no fog, no rain nor snow. The sky is an 
eternally black space, vaultless, jeweled with stars by 
day as by night. 

Let us suppose that we arrive among these savage 
249 



ASTRONOMY FOR AMATEURS 

steppes at daybreak: the lunar day is fifteen times longer 
than our own, because the Sun takes a month to illumi- 
nate the entire circuit of the Moon; there are no less 
than 354 hours from the rising to the setting of the Sun. 
If we arrive before the sunrise, there is no aurora to 
herald it, for in the absence of atmosphere there can be 
no sort of twilight. Of a sudden on the dark horizon 
come flashes of the solar light, striking the summits of 
the mountains, while the plains and valleys are still in 
darkness. The light spreads slowly, for while on the 
Earth in central latitudes the Sun takes only two minutes 
and a quarter to rise, on the Moon it takes nearly an 
hour, and in consequence the light it sends out is very 
weak for some minutes, and increases excessively 
slowly. It is a kind of aurora, but lasts a very short 
time, for when at the end of half an hour, the solar disk 
has half risen, the light appears as intense to the eye 
as when it is entirely above the horizon; the radiant 
orb is seen with its protuberances and its burning at- 
mosphere. It rises slowly, like a luminous god, in the 
depths of the black sky, a profound and formless sky 
in which the stars shine all day, since they are not hidden 
by any atmospheric veil such as conceals them from us 
during the daylight. 

The absence of'sensible atmosphere must produce 
an effect on the temperature of the Moon analogous to 

250 



THE MOON 



that perceived on the high mountains of our globe, where 
the rarefaction of the air does not permit the solar heat 





S 


^ 


^^^ 


M^^lKa^K^ 


I^Hi 






m 


|i 


^m 


^^^Ph 


^^B 






1 


1 


i 


^H 


B 






i 


1 


Wk 


m^^m 


^B 






1 


m 


M 


^^^p 


^H 






1 


1 


H 


^^^m 


^p 




v%^^Kk 


1 


1 


1 


^H 


9 






1 


1 


1 


H 


1 





Fig. 72. — The Lunar Apennines. 

to concentrate itself upon the surface of the soil, as it 
does below the atmosphere, which acts as a forcing- 
house: the Sun's heat is not kept in by anything, and 

251 



ASTRONOMY FOR AMATEURS 

incessantly radiates out toward space. In all probability 
the cold is extremely and constantly rigorous, not only 
during the nights, which are fifteen times longer than 
our own, but even during the long days of sunshine. 

We give two different drawings to represent these cu- 
rious aspects of lunar topography. The first (Fig. 72) 
is taken in the neighborhood of the Apennines, and 
shows a long chain of mountains beneath which are 
three deep rings, Archimedes, Aristillus, and Autolycus: 
the second (Fig. 73) depicts the lunar ring of Flam- 
marion,* whose outline is constructed of dismantled 
ramparts, and whose depths are sprinkled with little 
craters. The first of these two drawings was made 
in England by Nasmyth, the second in Germany by 
Krieger: they both give an exact idea of what one 
sees in the telescope with different modes of solar illu- 
mination. 

In the Moon's always black and starry sky a majestic 
star that is not visible from the Earth, and exhibits 
this peculiarity that it is stationary in the Heavens, while 
all the others pass behind it, may constantly be admired, 
by day as well as by night; and it is also of considerable 

* My readers are charged not to speak of this property (which is fairly ex- 
tensive), lest the Budget Commission, at the end of its resources, should be 
tempted to put on an unexpected tax. This ring, which the astronomers 
presented to me in the year 1887, is almost in the center of the lunar disk, to 
the north of Ptolemy and Herschel. 

252 



THE MOON 

apparent magnitude. This orb, some four times as 
large as the Moon in diameter, and thirteen to fourteen 
times more extensive in surface, is our Earth, which 
presents to the Moon a sequence of phases similar to 




Fig. 73. — Flammarion's Lunar Ring. 

those which our sateUite presents to us, but in the 
inverse direction. At the moment of New Moon, the 
Sun fully illuminates the terrestrial hemisphere turned 
toward our satellite, and we get ''Full Earth'''; at the 

253 



ASTRONOMY FOR AMATEURS 

time of Full Moon, on the contrary, the non-illuminated 
hemisphere of the Earth is turned toward the satellite, 
and we get ''New Earth": when the Moon shows us 
first quarter^ the Earth is in last quarter, and so on. 
The drawing subjoined gives an idea of these aspects. 

What a curious sight our globe must be during this 
long night of fourteen times twenty-four hours! Inde- 




FiG. 74. — Lunar landscape with the Earth in the sky. 

pendent of its phases, which bring it from first quarter 
to full earth for the middle of the night, and from full 
earth to last quarter for sunrise, how interested we 
should be to see it thus stationary in the sky, and 
turning on itself in twenty-four hours. 

Yes, thanks to us, the inhabitants of the lunar hemi- 
sphere turned toward us are gratified by the sight of a 

254 



THE MOON 

splendid nocturnal torch, doubtless less white than our 
own despite the clouds with which the terrestrial globe is 
studded, and shaded in a tender tone of bluish emerald- 
green. The royal orb of their long nights, the Earth, 
gives them moonlight of unparalleled beauty, and we 
may say without false modesty that our presence in the 
lunar sky must produce marvelous and absolutely fairy- 
like effects. 

Maybe, they envy us our globe, a dazzling dwelling- 
place whose splendor radiates through space; they see 
its greenish clarity varying with the extent of cloud 
that veils its seas and continents, and they observe its 
motion of rotation, by which all the countries of our 
planet are revealed in succession to its admirers. 

We are talking of these pageants seen from the Moon, 
and of the inhabitants of our satellite as if they really 
existed. The sterile and desolate aspect of the lunar 
world, however, rather brings us to the conclusion that 
such inhabitants are non-existent, although we have 
no authorization for affirming this. That they have 
existed seems to me beyond doubt. The lunar vol- 
canoes had a considerable activity, in an atmosphere 
that allowed the white volcanic ashes to be carried a long 
way by the winds, figuring round the craters the stellar 
rays that are still so striking. These cinders were 
spread over the soil, preserving all its asperities of outline, 

255 



ASTRONOMY FOR AMATEURS 

a little heaped up on the side to which they were im- 
pelled. The magnificent photographs recently made at 
the Paris Observatory by MM. Loewy and Puiseux are 
splendid evidence of these projections. In this era of 
planetary activity there were liquids and gases on the 
surface of the lunar globe, which appear subsequently 
to have been entirely absorbed. Now the teaching of 
our own planet is that Nature nowhere remains infertile, 
and that the production of Life is a law so general and 
so imperious that life develops at its own expense, sooner 
than abstain from developing. Accordingly, it is diffi- 
cult to suppose that the lunar elements can have re- 
mained inactive, when only next door they exhibited 
such fecundity upon our globe. Yes, the Moon has 
been inhabited by beings doubtless very different from 
ourselves, and perhaps may still be, although this globe 
has run through the phases of its astral life more rapidly 
than our own, and the daughter is relatively older than 
the mother. 

The duration of the life of the worlds appears to 
have been in proportion with their masses. The Moon 
cooled and mineralized more quickly than the Earth. 
Jupiter is still fluid. 

The progress of optics brings us already very close 
to this neighboring province. 'Tis a pity we can not 
get a little nearer! 

256 



THE MOON 

A telescopic magnification of 2,000 puts the Moon at 
^M"0^^~ or 192 kilometers (some 120 miles) from our 
eye. Practically we can obtain no more, either from 
the most powerful instruments, or from photographic 
enlargements. Sometimes, exceptionally, enlargements 
of 3,000 can be used. This = ^ 3 ^~ ^^ ^^^ kilometers 
(some 80 miles). Undoubtedly, this is an admirable 
result, which does the greatest honor to human intelli- 
gence. But it is still too far to enable us to determine 
anything in regard to lunar life. 

Any one who likes to be impressed by grand and 
magnificent sights may turn even a modest field-glass 
upon our luminous satellite, at about first quarter, when 
the relief of its surface, illuminated obliquely by the Sun, 
is at its greatest value. If you examine our neighbor 
world at this period, for choice at the hour of sunset, 
you will be astonished at its brilliancy and beauty. Its 
outlines, its laces, and embroideries, give the image of a 
jewel of shining silver, translucent, fluid, palpitating in 
the ether. Nothing could be more beautiful, nothing 
purer, and more celestial, than this lunar globe floating 
in the silence of space, and sending back to us as in some 
fairy dream the solar illumination that floods it. But 
yesterday I received the same impression, watching a 
great ring half standing out, and following the progress 
of the Sun as it mounted the lunar horizon to touch these 

257 



ASTRONOMY FOR AMATEURS 

silvered peaks. And I reflected that it is indeed incon- 
ceivable that i^WoV ^f ^^^ inhabitants of our planet 
should pass their lives w^ithout ever having attended to 
this pageant, nor to any of those others v^hich the di- 
vine Urania scatters so profusely beneath the wonder- 
ing gaze of the observers of the Heavens. 



258 



CHAPTER X 

THE ECLIPSES 

Among all the celestial phenomena at which it may 
be our lot to assist during our contemplation of the 
universe, one of the most magnificent and imposing is 
undoubtedly that which we are now going to consider. 

The hirsute comets, and shooting stars with their 
graceful flight, captivate us with a m\'sterious and some- 
times fantastic attraction. W e ^ladlv allow our thoughts, 
mute questioners of the mysteries of the firmament, to 
rest upon the brilliant, golden trail they leave behind 
them. These unknown travelers bring a message from 
eternity; they tell us the tale of their distant journeys. 
Children of space, their ethereal beauty speaks of the 
immensity of the universe. 

The eclipses, on the other hand, are phenomena that 
touch us more nearly, and take place in our vicinity. 

In treating of them, we remain between the Earth 
and the Moon, in our little province, and witness the 
picturesque effects of the combined movements of our 
satellite around us. 

Have you ever seen a total eclipse of the Sun ? 
18 259 



ASTRONOMY FOR AMATEURS 

The sky is absolutely clear: no fraction of cloud 
shadows the solar rays. The azure vault of the firma- 
ment crowns the Earth with a dome of dazzling light. 
The fires of the orb of day shed their beneficent influence 
generally upon the world. 

Yet, see! The radiance diminishes. The luminous 
disk of the Sun is gradually corroded. Another disk, as 
black as ink, creeps in front of it, and little by little 
invades it entirely. The atmosphere takes on a wan, 
sepulchral hue; astonished nature is hushed in pro- 
found silence; an immense veil of sadness spreads over 
the world. Night comes on suddenly, and the stars 
shine out in the Heavens. It seems as though by some 
mysterious cataclysm the Sun had disappeared forever. 
But this tribulation is soon over. The divine orb is not 
extinct. A flaming jet emerges from the shadow, an- 
nouncing his return, and when he reappears we see 
that he has lost nothing in splendor or beauty. He is 
still the radiant Apollo, King of Day, watching over the 
life of the planetary worlds. 

This sudden night, darkening the Heavens in the 
midst of a fine day, can not fail to produce a vivid im- 
pression upon the spectators of the superb phenomenon. 

The eclipse lasts only for a few moments, but long 
enough to make a deep impression upon our minds, and 
indeed to inspire anxious spirits with terror and agita- 

260 



THE ECLIPSES 

tion — even at this epoch, when we know that there is 
nothing supernatural or formidable about it. 

In former days. Humanity would have trembled, in 
uneasy consternation. Was it a judgment from Heaven .? 
Must it not be the work of some invisible hand throwing 
the somber veil of night over the celestial torch ? 

Had not the Earth strayed off her appointed path, 
and were we not all to be deprived eternally of the light 
of our good Sun ? Was some monstrous dragon perhaps 
preparing to devour the orb of day ? 

The fable of the dragon devouring the Sun or Moon 
during the eclipses is universal in Asia as in Africa, and 
still finds acceptance under more than one latitude. 
But our readers already know that we may identify the 
terrible celestial dragon with our gentle friend the 
Moon, who would not be greatly flattered by the com- 
parison. 

We saw in the preceding lesson that the Moon 
revolves round us, describing an almost circular orbit 
that she travels over in about a month. In consequence 
of this motion, the nocturnal orb is sometimes between 
the Sun and the Earth, sometimes behind us, sometimes 
at a right angle in relation to the Sun and the Earth. 
Now, the eclipses of the Sun occur invariably at the time 
of New Moon, when our satellite passes between the Sun 
and ourselves, and the eclipses of the Moon, at the 

261 



ASTRONOMY FOR AMATEURS 

moment of Full Moon, when the latter is opposite to the 
Sun, and behind us. 

This fact soon enabled the astronomers of antiquity 
to discover the causes to which eclipses are due. 

The Moon, passing at the beginning of its revolution 
between the Sun and the Earth, may conceal a greater 
or lesser portion of the orb of day. In this case there is 
an eclipse of the Sun. On the other hand, when it is 
on the other side of the Earth in relation to the Sun, at 
the moment of Full Moon, our planet may intercept the 
solar rays, and prevent them from reaching our satellite. 
The Moon is plunged into the shadow of the Earth, and 
is then eclipsed. Such is the very simple explanation 
of the phenomenon. But why is there not an eclipse of 
the Sun at each New Moon, and an eclipse of the Moon 
at each Full Moon ? 

If the Moon revolved round us in the same plane as 
the Earth round the Sun, it would eclipse the Sun at 
each New Moon, and would be itself eclipsed in our 
shadow at each Full Moon. But the plane of the lunar 
orbit dips a little upon the plane of the terrestrial orbit, 
and the eclipses can only be produced when the New 
Moon or the Full Moon occur at the line of intersection 
of these two planes, /". ^., when the Sun, the Moon, and 
the Earth are upon the same straight line. In the ma- 
jority of cases, instead of interposing itself directly in 

262 



THE ECLIPSES 

front of the sovereign of our system, our satellite passes 
a little above or a little below him, just as its passage 
behind us is nearly alvs^ays effected a little above or 
below the cone of shadow that accompanies our planet, 
opposite the Sun. 

When the Moon intervenes directly in front of the 
Sun, she arrests the light of the radiant orb, and con- 
ceals a greater or less portion of the solar disk. The 
eclipse is partial if the Moon covers only a portion of 
the Sun; total if she covers it entirely; annular, if the 
solar disk is visible all round the lunar disk, as appears 
when the Moon, in her elliptical orbit, is beyond medium 
distance, toward the apogee. 

On the other hand, when the Moon arrives imme- 
diately within the cone of shadow that the Earth projects 
behind it, it is her turn to be eclipsed. She no longer 
receives the rays of the Sun, and this deprivation is the 
more marked in that she owes all her brilliancy to the 
light of the orb of day. The Moon's obscurity is com- 
plete if she is entirely plunged into the cone of shadow. 
In this case, the eclipse is total. But if a portion of her 
disk emerges from the cone, that part remains illumi- 
nated while the light of the other dies out. In that case 
there is a partial eclipse, and the rounded form of the 
Earth's shadow can be seen projected upon our satellite, 
a celestial witness to the spherical nature of our globe. 

263 



ASTRONOMY FOR AMATEURS 

Under certain conditions, then, the Moon can 
deprive us of the luminous rays of the Sun, by con- 
cealing the orb of day, and in other cases is herself 
effaced in crossing our shadow. Despite the fables, 
fears, and anxieties it has engendered, this phenomenon 
is perfectly natural: the Moon is only playing hide-and- 
seek with us — a very harmless amusement, as regards 
the safety of our planet. 

But as we said just now, these phenomena formerly 
had the power of terrifying ignorant mortals, either 
when the orb of light and life seemed on the verge of 
extinction, or when the beautiful Phoebus was covered 
with a veil of crape and woe, or took on a deep cop- 
pery hue. 

It would take a volume to describe all the notable 
events w^hich have been influenced by eclipses, some- 
times for good, more often with disastrous consequences 
The recital of these tragic stories would not be devoid of 
interest; it would illustrate the possibilities of ignorance 
and superstition, and the power man gains from intel- 
lectual culture and scientific study. 

Herodotus records that the Scythians, having some 
grievance against Cyaxarus, King of the Medes, re- 
venged themselves by serving up the limbs of one of his 
children, whom they had murdered, at a banquet as 
rare game. The scoundrels who committed this atro- 

264 



THE ECLIPSES 

clous crime took refuge at the Court of the King of 
Lydia, who was ill judged enough to protect them. 
War was accordingly declared between the Medes and 
Lydians, but a total eclipse of the Sun occurring just 
when the battle was imminent, had the happy effect of 
disarming the combatants, who prudently retired each 
to their own country. This eclipse, which seems to 
have occurred on May 28, 584 b. c, had been predicted 
by Thales. The French painter Rochegrosse has 
painted a striking picture of the scene (Fig. 75). 

In the year 413 b. c. the Athenian General Nicias 
prepared to return to Greece after an expedition to 
Sicily. But, terrified by an eclipse of the Moon, and 
fearing the malign influence of the phenomenon, he put 
off his departure, and lost the chance of retreat. This 
superstition cost him his life. The Greek army was 
destroyed, and this event marks the commencement of 
the decadence of Athens. 

In 331 B. c. an eclipse of the Moon disorganized the 
troops of Alexander, near Arbela, and the great Mace- 
donian Captain had need of all his address to reassure 
his panic-stricken soldiers. 

Agathocles, King of Syracuse, blocked by the Car- 
thaginians in the port of this city, had the good fortune 
to escape, but was disturbed on the second day of his 
flight by the arrival of a total eclipse of the Sun which 

265 



ASTRONOMY FOR AMATEURS 

alarmed his companions. ''What are you afraid of?" 
said he, spreading his cloak in front of the Sun. ''Are 




Fig. 75. — Battle between the Medes and Lydians arrested 
by an Eclipse of the Sun. 

266 



THE ECLIPSES 

you alarmed at a shadow?" (This eclipse seems to be 
that of August 15, 309, rather than that of March 2, 

310-) 

On June 29, 1033, an epoch at which the approaching 

end of the world struck terror into all hearts, an annular 
eclipse of the Sun occurring about midday frustrated 
the designs of a band of conspirators who intended to 
strangle the Pope at the altar. This Pope was Bene- 
dict IX, a youth of less than twenty, whose conduct 
is said to have been anything but exemplary. The 
assassins, terrified at the darkening of the Sun, dared 
not touch the Pontiff, and he reigned till 1044.* 

On March i, 1504, a lunar eclipse saved the life of 
Christopher Columbus. He was threatened with death 
by starvation in Jamaica, where the contumacious 
savages refused to give him provisions. Forewarned of 
the arrival of this eclipse by the astronomical almanacs, 
he threatened to deprive the Caribs of the light of the 
Moon — and kept his word. The eclipse had hardly 
begun when the terrified Indians flung themselves at his 
feet, and brought him all that he required. 

In all times and among all people we find traces of 
popular superstitions connected with eclipses. Here, 
the abnormal absence of the Moon's light is regarded 
as a sign of divine anger: the humble penitents betake 

* *<La fin du Monde." Flammarion, p. i86. 
267 



ASTRONOMY FOR AMATEURS 

themselves to prayer to ward off the divine anger. 
There, the cruelty of the dread dragon is to be averted: 
he must be chased away by cries and threats, and the 
sky is bombarded with shots to deliver the victim from 
his monstrous oppressor. 

In France the announcement of a solar eclipse for 
August 21, 1560, so greatly disturbed our ancestors' 
peace of mind as to make them idiotic. Preparations 
were made for assisting at an alarming phenomenon 
that threatened Humanity with deadly consequences! 
The unhappy eclipse had been preceded by a multitude 
of ill omens! Some expected a great revolution in the 
provinces and in Rome, others predicted a new universal 
deluge, or, on the other hand, the conflagration of the 
world; the most optimistic thought the air would be 
contaminated. To preserve themselves from so many 
dangers, and in accordance with the physicians' orders, 
numbers of frightened people shut themselves up in 
tightly closed and perfumed cellars, where they awaited 
the decrees of Fate. The approach of the phenomenon 
increased the panic, and it is said that one village cure^ 
being unable to hear the confessions of all his flock, 
who wanted to discharge their souls of sin before taking 
flight for a better world, was fain to tell them ''there was 
no hurry, because the eclipse had been put off a fort- 
night on account of the number of penitents"! 

268 



THE ECLIPSES 



These fears and terrors are still extant among 
ignorant peoples. In the night of February 27, 1877, 
an eclipse of the Moon produced an indescribable panic 




Fig. ^6, — Eclipse of the Moon at Laos (February 27, 1877). 

among the inhabitants of Laos (Indo-China). In order 
to frighten off the Black Dragon, the natives fired shots 
at the half-devoured orb, accompanying their volley v^ith 

269 



ASTRONOMY FOR AMATEURS 

the most appalling yells. Dr. Harmand has memo- 
rialized the scene in the lively sketch given on p. 269. 

During the solar eclipse of March 15, 1877, an an- 
alogous scene occurred among the Turks, who for the 
moment forgot their preparations for vs^ar v^ith Russia, 
in order to shoot at the Sun, and deliver him from the 
toils of the Dragon. 

The lunar eclipse of December 16, 1880, was not 
unnoticed at Tackhent (Russian Turkestan), where it 
was received with a terrific din of saucepans, samovars 
and various implements struck together again and again 
by willing hands that sought to deliver the Moon from 
-the demon Tchaitan who was devouring her. 

In China, eclipses are the object of imposing cere- 
monies, whose object is to reestablish the regularity of 
the celestial motions. Since the Emperor is regarded 
as the Son of Heaven, his government must in some sort 
be a reflection of the immutable order of the sidereal 
harmonies. As eclipses were regarded by astrologers 
as disturbances of the divine order^ their appearance 
indicates some irregularity in the government of the 
Celestial Empire. Accordingly, they are received with 
all kinds of expiatory ceremonies prescribed thousands 
of years ago, and still in force to-day. 

In the twentieth century, as in the nineteenth, the 
eighteenth, or in ancient epochs, the same awe and terror 

270 



THE ECLIPSES 

operates upon the ignorant populations who abound 
upon the surface of our planet. 

To return to astronomical realities. 

We said above that these phenomena were produced 
when the Full Moon and the New Moon reached the 
line of intersection, known as the line of nodes, when 
the plane of the lunar orbit cuts the plane of the 
ecliptic. As this line turns and comes back in the same 
direction relatively to the Sun at the end of eighteen 
years, eleven days, we have only to register the eclipses 
observed during this period in order to know all that 
will occur in the future, and to find such as happened 
in the past. This period was known to the Greeks 
under the name of the Metonic Cycle, and the Chal- 
deans employed it three thousand years ago under the 
name of Saros. 

On examining this cycle, composed of 223 lunations, 
we see that there can not be more than seven eclipses in 
one year, nor less than two. When there are only two, 
they are eclipses of the Sun. 

The totality of a solar eclipse can not last more than 
seven minutes, fifty-eight seconds at the equator, and 
six minutes, ten seconds in the latitude of Paris. The 
Moon, on the contrary, may be entirely eclipsed for 
nearly two hours. 

Eclipses of the Sun are very rare for a definite spot. 
271 



ASTRONOMY FOR AMATEURS 

Thus not one occurred for Paris during the whole of the 
nineteenth century, the last which happened exactly 
above the capital of France having been on May 22, 
1724. I have calculated all those for the twentieth cen- 
tury, and find that two will take place close to Paris, on 
April 17, 1912, at eighteen minutes past noon (total for 
Choisy-le-Roi, Longjumeau, and Dourdan, but very 
brief: seven seconds), and August 11, 1999, at 10.28 
A. M. (total for Beauvais, Compiegne, Amiens, St. 
Quentin, fairly long: two minutes, seventeen seconds). 
Paris itself will not be favored before August 12, 2026. 
In order to witness the phenomenon, one must go and 
look for it. This the author did on May 28, 1900, in 
Spain. 

The progress of the lunar shadow upon the surface 
of the Earth is traced beforehand on maps that serve 
to show the favored countries for which our satellite will 
dispense her ephemeral night. The above figure shows 
the trajectory of the total phase of the 1900 eclipse in 
Portugal, Spain, Algeria, and Tunis. 

The immutable splendor of the celestial motions had 
never struck the author so impressively as during the 
observation of this grandiose phenomenon. With the 
absolute precision of astronomical calculations, our 
satellite, gravitating round the Earth, arrived upon the 
theoretical line drawn from the orb of day to our planet, 

272 




273 



ASTRONOMY FOR AMATEURS 

and interposed itself gradually, slowly, and exactly, in 
front of it. The eclipse was total, and occurred at the 
moment predicted by calculation. Then the obscure 
globe of the Moon pursued its regular course, discovered 
the radiant orb behind, and gradually and slowly com- 
pleted its transit in front of him. Here, to all observers, 
was a double philosophical lesson, a twofold impression: 
that of the greatness, the omnipotence of the inexorable 
forces that govern the universe, and that of the inex- 
orable valor of man, of this thinking atom straying upon 
another atom, who by the travail of his feeble intelligence 
has arrived at the knowledge of the laws by which he^ 
Hke the rest of the world, is borne away through space, 
through time, and through eternity. 

The line of centrality passed through Elche, a pic- 
turesque city of 30,000 inhabitants, not far from Ali- 
cante, and we had chosen this for our station on 
account of the probability of fine weather. 

From the terrace of the country house of the hos- 
pitable Mayor, a farm transformed into an observatory 
by our learned friend. Count de la Baume Pluvinel, 
there were no obstacles between ourselves and any part 
of the sky or landscape. The whole horizon lay before 
us. In front was a town of Arab aspect framed in a 
lovely oasis of palm-trees; a little farther off, the blue sea 
beyond the shores of Alicante and Murcia : on the other 

274 



THE ECLIPSES 

side a belt of low mountains, and near us fields and 
gardens. A Company of the Civic Guard kept order, 
and prevented the entrance of too many curious visitors, 
of v^hom over ten thousand had arrived. 

At the moment when the first contact of the lunar 
disk with the solar disk was observed in the telescope, 
we fired a gun, in order to announce the precise com- 
mencement of the occultation to the 40,000 persons who 
were awaiting the phenomenon, and to discover what 
diflPerence would exist between this telescopic observa- 
tion and those made with the unaided eyes (protected 
simply by a bit of smoked glass) of so many improvised 
spectators. This had already been done by Arago at 
Perpignan in 1842. The verification was almost im- 
mediate for the majority of eyes, and may be estimated 
at eight or ten seconds. So that the commencement of 
the eclipse was confirmed almost as promptly for the 
eye as with the astronomical instruments. 

The sky was splendidly clear; no cloud, no mist, 
deep blue; blazing Sun. The first period of the eclipse 
showed nothing particular. It is only from the mo- 
ment when more than half the solar disk is covered by 
the lunar disk that the phenomenon is imposing in its 
grandeur. At this phase, I called the attention of the 
people standing in the court to the visibility of the 
stars, and indicating the place of Venus in the sky asked 
19 275 



ASTRONOMY FOR AMATEURS 

if any with long sight could perceive her. Eight at once 
responded in the affirmative. It should be said that the 
planet w^as at that time at its period of maximum bril- 
liancy, w^hen for observers blessed v^ith good sight, it is 
aWays visible to the unaided eye. 

When some three-quarters of the Sun were eclipsed, 
the pigeons which had flown back to the farm huddled 
into a corner, and made no further movement. They 
told me that evening that the fowls had done the same 
a little later, returning to the hen-house as though it 
had been night, and that the small children (who were 
very numerous at Elche, where the population is cer- 
tainly not diminishing) left off their games, and came 
back to their mothers' skirts. The birds flew anxious- 
ly to their nests. The ants in one garden were exces- 
sively agitated, no doubt disconcerted in their strategics. 
The bats came out. 

A few days before the eclipse I had prepared the 
inhabitants of this part of Spain for the observation of 
the phenomenon by the following description, which 
sums up the previous accounts of the astronomers: 

''The spectacle of a total eclipse of the Sun is one 
of the most magnificent and imposing that it is possible 
to see in nature. At the exact moment indicated by 
calculation, the Moon arrives in front of the Sun, eats 
into it gradually, and at last entirely covers it. The 
. 276 



THE ECLIPSES 

light of the day lessens and is transformed. A sense 
of oppression is felt by all nature, the birds are hushed, 
the dog takes refuge with his master, the chickens hide 
beneath their mother's wing, the wind drops, the tem- 
perature falls, an appalling stillness is everywhere per- 
ceptible, as though the universe were on the verge of 
some imminent catastrophe. Men's faces assume a 
cadaverous hue similar to that given at night by the 
flame of spirits of wine and salt, a livid funereal light, 
the sinister illumination of the world's last hour. 

'* At the moment when the last line of the solar cres- 
cent disappears, we see, instead of the Sun, a black disk 
surrounded with a splendid luminous aureole shooting 
immense jets into space, with roseate flames burning 
at the base. 

''A sudden night has fallen on us, a weird, wan night 
in which the brightest of the stars are visible in the 
Heavens. The spectacle is splendid, grandiose, solemn, 
and sublime." 

This impression was actually felt by us all, as 
may be seen from the following notes, written in my 
schedule of observation during the event, or immedi- 
ately after: 

'' 3*50 P- M. Light very weak, sky leaden gray, 
mountains standing out with remarkable clearness 
from the horizon, and seeming to approach us. 

277 



ASTRONOMY FOR AMATEURS 

''3.55 P.M. Fall of temperature very apparent. 
Cold wind blowing through the atmosphere. 

"3.56 P.M. Profound silence through nature, 
which seems to participate in the celestial phenomenon. 
Silence in all the groups. 

'' 3.57 p. M. Light considerably diminished, becom- 
ing wan, strange, and sinister. Landscape leaden gray, 
sea looks black. This diminution of light is not that of 
every day after the sunset. There is, as it were, a tint of 
sadness spread over the whole of nature. One becomes 
accustomed to it, and yet while we know that the occulta- 
tion of the Sun by the Moon is a natural phenomenon, 
we can not escape a certain sense of uneasiness. The 
approach of some extraordinary spectacle is imminent." 

At this point we examined the effects of the solar 
light upon the seven colors of the spectrum. In order 
to determine as accurately as possible the tonality of 
the light of the eclipse, I had prepared seven great sheets, 
each painted boldly in the colors of the spectrum, violet, 
indigo, blue, green, yellow, orange, red; and a similar 
series in pieces of silk. These colors were laid at our 
feet upon the terrace where my wife, as well as Countess 
de la Baume, were watching with me. We then saw the 
first four disappear successively and entirely and turn 
black in a few seconds, in the following order: violet, 
indigo, blue, green. The three other colors were con- 

278 



THE ECLIPSES 

siderably attenuated by the darkness, but remained 
visible. 

It should be noted that in the normal order of things 
— that is, every evening — the contrary appears; violet 
remains visible after the red. 

This experiment shows that the last light emitted 
by the eclipsed Sun belongs to the least refrangible rays, 
to the greatest wave-lengths, to the slowest vibrations, 
to the yellow and red rays. Such therefore is the pre- 
dominating color of the solar atmosphere. 

This experiment completed, we turn back to the 
Sun. Magical and splendid spectacle! Totality has 
commenced, the Sun has disappeared, the black disk 
of the Moon covers it entirely, leaving all round it a 
magnificent corona of dazzling light. One would sup- 
pose it to be an annular eclipse, with the difference that 
this can be observed with the naked eye, without fatigue 
to the retina, and drawn quietly. 

This luminous coronal atmosphere entirely sur- 
rounds the solar disk, at a pretty equal depth, equivalent 
to about the third of half the solar diameter. It may 
be regarded as the Sun's atmosphere. 

Beyond this corona is an aureole, of vaster glory but 
less luminous, which sends out long plumes, principally 
in the direction of the equatorial zone of the Sun, and of 
the belt of activity of the spots and prominences. 

279 



ASTRONOMY FOR AMATEURS 

At the summit of the disk it is conical in shape. 
Below it is double, and its right-hand portion ends in a 
point, not far from Mercurv, which shines like a dazzling 
star of first magnitude, and seems placed there expressly 
to o-ive us the extent and direction of the solar aureole. 

o 

I draw these various aspects (which, moreover, 
change with the movement of the Moon), and what 
strikes me most is the distinction in light between this 
aureole and the coronal atmosphere; the latter appears 
to be a brilliant silvery white, the former is grayer and 
certainly less dense. 

My impression is that there are tiuo solar envelopes 
of entirely different nature, the corona belonging to the 
globe of the Sun, and forming its atmosphere properly 
so-called, very luminous; the aureole formed of particles 
that circulate independently round it, probably arising 
from eruptions, their form as a whole being possibly due 
to electric or magnetic forces, counterbalanced by re- 
sistances of various natures. In our own atmosphere 
the volcanic eruptions are distinct from the aerial 
envelope. 

The general configuration of this external halo, 
spreading more particularly in the equatorial zone, is 
sufficiently like that of the eclipse of 1889, published in 
my Popular Astronomy, which also corresponded with 
a minimum of solar energy. The year igoo is in fact 

280 




Fig. ^ 8. — Total eclipse of the Sun, Mav 28, 1900, 

as observed from Elche 1 Spain i . 



281 



ASTRONOMY FOR AMATEURS 

close upon the mimimum of the eleven-year period. 
This equatorial form is, moreover, what all the astrono- 
mers w^ere expecting. 

There can no longer be the slightest doubt that the 
solar envelope varies v^ith the activity of the Sun. . . . 

" But the total eclipse lasted a much shorter time 
than I have taken to v^rite these lines. The seventy- 
nine seconds of totality are over. A dazzling light 
bursts from the Sun, and tells that the Moon pursuing 
its orbit has left it. The splendid sight is over. It has 
gone like a shadov^. 

"Already over! It is almost a disillusion. Nothing 
beautiful lasts in this world. Too sad! If only the 
celestial spectacle could have lasted two, three, or four 
minutes! It was too short. ... 

"Alas! we are forced to take things as they are. 

"The surprise, the oppression, the terror of some, 
the universal silence are over. The Sun reappears in 
his splendor, and the life of nature resumes its momen- 
tarily suspended course. 

" While I was making my drawing, M. TAbbe 
Moreux, my colleague from the Astronomical Society of 
France, who accompanied me to Spain for this observa- 
tion, was taking one of his own, without any reciprocal 
communication. These two sketches are alike, and 
confirmatory. 

282 



THE ECLIPSES 

"The differential thermometers that I exposed to 
the Sun, hanging freely, and protected from reflection 
from the ground, were read every five minutes. The 
black thermometer w^ent dov^n from 33.1° to 20.7°, that 
is 12.4°; the v^hite from 29° to 20.2° — that is, 8.8°. The 
temperature in the shade only varied three degrees. 

"The light received during totality v^as due: first, 
to the luminous envelope of the Sun; second, to that 
of the terrestrial atmosphere, illuminated at forty kilo- 
meters (tv^enty-five miles) on the one side and the other 
of the line of centrality. It appeared to be inferior to 
that of the Full Moon, on account of the almost sud- 
den transition. But, in reality, it v^as more intense, 
for only first-magnitude stars were visible in the sky, 
whereas on a night of full moon, stars of second, and 
even of third magnitude are visible. We recognized, 
among others, Venus, Mercury, Sirius, Procyon, Ca- 
pella, Rigel, Betelgeuse." 

From these notes, taken on the spot, it is evident that 
the contemplation of a total eclipse of the Sun is one of 
the most marvelous spectacles that can be admired upon 
our planet. 

Some persons assured me that they saw the shadow 
of the Moon flying rapidly over the landscape. My 
attention was otherwise occupied, and I was unable to 

283 



ASTRONOMY FOR AMATEURS 

verify this interesting observation. The shadow of the 
Moon in effect took only eleven minutes (3.47 P. m. to 
3.58 p. M.) to traverse the Iberian Peninsula from Porto to 
Alicante, /. e.^ a distance of 766 kilometers (475 miles). 
It must therefore have passed over the ground at a 
velocity of sixty-nine kilometers per minute, or 1,150 
meters per second, a speed higher than that of a bullet. 
It can easily be vs^atched from afar, on the mountains. 

Some weeks previous to this fine eclipse, when I in- 
formed the Spaniards of the belt along which it could 
be observed, I had invited them to note all the interesting 
phenomena they might witness, including the effects 
produced by the eclipse upon animals. Birds returned 
hurriedly to their nests, swallows lost themselves, sheep 
huddled into compact packs, partridges were hypnotized, 
frogs croaked as if it were night, fowls took refuge in the 
hen-house, and cocks crowed, bats came out, and were 
surprised by the sun, chicks gathered under their 
mothers' wing, cage-birds ceased their songs, some dogs 
howled, others crept shivering to their masters' feet, ants 
returned to the ant-heap, grasshoppers chirped as at 
sunset, pigeons sank to the ground, a swarm of bees 
went silently back to their hive, and so on. 

These creatures behaved as though the night had 
come, but there were also signs of fear, surprise, even 
of terror, differing only '*in degree" from those mani- 

284 



THE ECLIPSES 

fested during the grandiose phenomenon of a total 
edipse by human beings unenlightened by a scientific 
education. 

At Madrid the ecHpse was only partial. The young 
King of Spain, Alfonso XIII, took care to photograph it, 
and I offer the photograph to my readers (Fig. 79), as this 
amiable sovereign 
did me the honor to 
give it me a few days 
after the eclipse. 

The technical 
results of these ob- 
servations of solar 
eclipses relate more 
especially to the 
elucidation of the 
grand problem of 
the physical consti- ^^^- 79— The Eclipse of May 28, 
1900, as photographed by King Al- 
tution of the Sun. ^^^^^ j^j„^ ^^ ^^^^.^^ 

We alluded to them 

in the chapter devoted to this orb. The last great total 

eclipses have been of immense value to science. 

The eclipses of the Moon are less important, less 
interesting, than the eclipses of the Sun. Yet their 
aspect must not be neglected on this account, and it 
may be said to vary for each eclipse. 

285 




ASTRONOMY FOR AMATEURS 

Generally speaking, our satellite does not disappear 
entirely in the Earth's cone of shadow, the solar rays 
are refracted round our globe by our atmosphere, and 
curving inward, illumine the lunar globe with a rosy 
tint that reminds one of the sunset. Sometimes, in- 
deed, this refraction does not occur, owing doubtless 
to lack of transparency in the atmosphere, and the 
Moon becomes invisible. This happened recently, on 
April II, 1903. 

For any spot, eclipses of the Moon are incomparably 
more frequent than eclipses of the Sun, because the cone 
of lunar shadow that produces the solar eclipses is not 
very broad at its contact with the surface of the globe 
(10, 20, 30, 50, 100 kilometers, according to the distance 
of the Moon), whereas all the countries of the Earth for 
which the Moon is above the horizon at the hour of the 
lunar eclipse are able to see it. It is at all times a 
remarkable spectacle that upKfts our thoughts to the 
Heavens, and I strongly advise my readers on no 
account to forego it. 



286 



CHAPTER XI 
ON METHODS 

How Celestial Distances are Determined, and how the 
Sun is Weighed 

I WILL not do my readers the injustice to suppose 
that they will be alarmed at the title of this Lesson, and 
that they do not employ some "method" in their own 
lives. I even assume that if they have been good enough 
to take me on faith when I have spoken of the distances 
of the Sun and Moon, and Stars, or of the weight of 
bodies at the surface of Mars, they retain some curiosity 
as to how the astronomers solve these problems. Hence 
it will be as interesting as it is useful to complete the 
preceding statements by a brief summary of the methods 
employed for acquiring these bold conclusions. 

The Sun seems to touch the Earth when it disappears 
in the purple mists of twilight: an immense abyss sepa- 
rates us from it. The stars go hand in hand down the 
constellated sky; and yet one can not think of their in- 
conceivable distance without a shiver. 

Our neighbor, Moon, floats in space, a stone's throw 
287 



ASTRONOMY FOR AMATEURS 

from us: but without calculation we should never know 
the distance, which remains an impassable desert to us. 

The best educated persons sometimes find it difficult 
to admit that these distances of Sun and Moon are better 
determined and more precise than those of certain points 
on our minute planet. Hence, it is of particular moment 
for us to give an exact account of the means employed 
in determining them. 

The calculation of these distances is made by '^ trian- 
gulation." This process is the same that surveyors 
use in the measurement of terrestrial distances. There 
is nothing very alarming about itc If the word repels 
us a little at first, it is from its appearance only. 

When the distance of an object is unknown, the only 
means of expressing its apparent size is by measurement 
of the angle which it subtends before our eyes. 

We all know that an object appears smaller, in 
proposition with its distance from us. This diminution 
is not a matter of chance. It is geometric, and propor- 
tional to the distance. Every object removed to a dis- 
tance of 57 times its diameter measures an angle of i 
degree, whatever its real dimensions. Thus a sphere i 
meter in diameter measures exactly i degree, if v/e see 
it at a distance of 57 feet. A statue measuring 1.80 
meters (about 5 ft. 8 in.) will be equal to an angle of i 
degree, if distant 57 times its height, that is to say, at 

288 



ON METHODS 

102.60 meters. A sheet of paper, size i decimeter, seen 
at 5.70 meters, represents the same magnitude. 

In length, a degree is the 57th part of the radius of 
a circle, i. e., from the circumference to the center. 

The measurement of an angle is expressed in parts 
of the circumference. Now, what is an angle of a de- 
gree ? It is the 360th part of any circumference. On 
a table 360 meters round, an angle of one degree is a 
centimeter, seen from the center of the table. Trace on 
a sheet of paper a circle 0.360 
meters round — an angle of i 
degree is a millimeter. 

If the circumference of a 

circus measuring 180 meters be 

Fig. 80. — Measurement 
divided into ^60 places, each 

, of Angles. 

measuring 0.50 meters in 

width, then when the circus is full a person placed at 
the center will see each spectator occupying an angle 
of I degree. The angle does not alter with the dis- 
tance, and whether it be measured at i meter, 10 
meters, 100 kilometers, or in the infinite spaces of 
Heaven, it is always the same angle. Whether a 
degree be represented by a meter or a kilometer, it al- 
ways remains a degree. As angles measuring less than 
a degree often have to be calculated, this angle has 
been subdivided into 60 parts, to which the name of 

289 




ASTRONOMY FOR AMATEURS 

minutes has been given, and each minute into 60 parts 
or seconds. Written short, the degree is indicated by 
a Httle zero (°) placed above the figure; the minute by 
an apostrophe (0, and the second by two (''). These 
minutes and seconds of arc have no relation Wixh the 
same terms as employed for the division of the duration 
of time. These latter ought never to be v^ritten with 
the signs of abbreviation just indicated, though jour- 
nalists nowadays set a somewhat pedantic example, by 
writing, ^. ^.,for an automobile race,4h. 18' 30''', instead 
of 4h. i8m. 30s. 

This makes clear the distinction between the relative 
measure of an angle and the absolute measures, such, 
for instance, as the meter. Thus, a degree may be 
measured on this page, while a second (the 3,600th part 
of a degree) measured in the sky may correspond to 
millions of kilometers. 

Now the measure of the Moon's diameter gives us 
an angle of a little more than half a degree. If it were 
exactly half a degree, we should know by that that it 
was 114 times the breadth of its disk away from us. 
But it is a little less, since we have more than half a 
degree (3i0j ^^i^ the geometric ratio tells us that the 
distance of our satellite is no times its diameter. 

Hence we have very simply obtained a first idea of 
the distance of the Moon by the measure of its diameter. 

290 



ON METHODS 

Nothing could be simpler than this method. The first 
step is made. Let us continue. 

This approximation tells us nothing as yet of the 
real distance of the orb of night. In order to know this 




Fig. 8i. — Division of the Circumference into 360 degrees. 

distance in miles, we need to know the width in miles of 

the lunar disk. 

This problem has been solved, as follows: 

Two observers go as far as possible from each other, 

and observe the Moon simultaneously, from two stations 

situated on the same meridian, but having a wide differ- 

20 291 



ASTRONOMY FOR AMATEURS 

ence of latitude. The distance that separates the two 
points of observation forms the base of a triangle, of 
which the two long sides come together on the Moon. 

It is by this proceeding that the distance of our 
satellite was finally established, in 1751 and 1752, by 
two French astronomers, Lalande and Lacaille; the 
former observing at Berlin, the latter at the Cape of 
Good Hope. The result of their combined observations 




Fig. 82. — Measurement of the distance of the Moon. 

showed that the angle formed at the center of the lunar 
disk by the half-diameter of the Earth is 57 minutes 
of arc (a little less than a degree). This is known as 
the parallax of the Moon. 

Here is a more or less alarming word; yet it is one 
that we can not dispense with in discussing the distance 
of the stars. This astronomical term will soon become 
familiar in the course of the present lesson, where it 

292 



ON METHODS 

will frequently recur, and always in connection with 
the measurement of celestial distances. *'Do not let us 
fear/' wrote Lalande in his Astronornie des Dames, 'Mo 
not let us fear to use the term parallax, despite its scien- 
tific aspect; it is convenient, and this term explains a 
very simple and very familiar effect.'' 

"If one is at the play," he continues, ''behind a 
woman whose hat is too large, and prevents one from 
seeing the stage [written a hundred years ago !], one 
leans to the left or right, one rises or stoops: all this is a 
parallax, a diversity of aspect, in virtue of which the hat 
appears to correspond with another part of the theater 
from that in which are the actors." " It is thus," he adds, 
''that there may be an eclipse of the Sun in Africa and 
none for us, and that we see the Sun perfectly, because 
we are high enough to prevent the Moon's hiding it 
from us." 

See how simple it is. This parallax of 57 min- 
utes proves that the Earth is removed from the Moon 
at a distance of about 60 times its half-diameter (pre- 
cisely, 60.27). From this to the distance of the Moon in 
kilometers is only a step, because it suffices to multiply 
the half-diameter of the Earth, which is 6,371 kilometers 
(3,950 miles) by this number. The distance of our 
satellite, accordingly, is 6,371 kilometers, multiplied by 
60.27 — that is, 384,000 kilometers (238,000 miles). The 

293 



ASTRONOMY FOR AMATEURS 

parallax of the Moon not only tells us definitely the dis- 
tance of our planet, but also permits us to calculate its 
real volume by the measure of its apparent volume. 
As the diameter of the Moon seen from the Earth sub- 
tends an angle of 31', v^hile that of the Earth seen from 
the Moon is 114', the real diameter of the orb of night 
must be to that of the terrestrial globe in the relation of 
273 to 1,000. That is a little more than a quarter, or 
3,480 kilometers (2,157 miles), the diameter of our planet 
being 12,742 kilometers (7,900 miles). 

This distance, calculated thus by geometry, is posi- 
tively determined with greater precision than that em- 
ployed in the ordinary measurements of terrestrial dis- 
tances, such as the length of a road, or of a raiWay. 
This statement may seem to be a romance to many, 
but it is undeniable that the distance separating the 
Earth from the Moon is measured with greater care 
than, for instance, the length of the road from Paris to 
Marseilles, or the weight of a pound of sugar at the 
grocer's. (And we may add without comment, that 
the astronomers are incomparably more conscientious 
in their measurements than the most scrupulous shop- 
keepers.) 

Had we conveyed ourselves to the Moon in order to 
determine its distance and its diameter directly, we 
should have arrived at no greater precision, and we 

294 



ON METHODS 

should, moreover, have had to plan out a journey which 
in itself is the most insurmountable of all the problems. 

The Moon is at the frontier of our little terrestrial 
province: one might say that it traces the limits of our 
domain in space. And yet, a distance of 384,000 kilo- 
meters (238,000 miles) separates the planet from the 
satellite. This space is insignificant in the immeasur- 
able distances of Heaven: for the Saturnians (if such 
exist!) the Earth and the Moon are confounded in one 
tiny star ; but for the inhabitants of our globe, the dis- 
tance is beyond all to v^hich we are accustomed. Let 
us try, however, to span it in thought. 

A cannon-ball at constant speed of 500 meters 
(547 yards) per second would travel 8 days, 5 hours to 
reach the Moon. A train started at a speed of one 
kilometer per minute, would arrive at the end of an 
uninterrupted journey in 384,000 minutes, or 6,400 
hours, or 266 days, 16 hours. And in less than the 
time it takes to write the name of the Queen of Night, 
a telegraphic message would convey our news to the 
Moon in one and a quarter seconds. 

Long-distance travelers who have been round the 
world some dozen times have journeyed a greater 
distance. 

The other stars (beginning with the Sun) are in- 
comparably farther from us. Yet it has been found 

295 



ASTRONOMY FOR AMATEURS 

possible to determine their distances, and the same 
method has been employed. 

But it will at once be seen that different measures 
are required in calculating the distance of the Sun, 388 
times farther from us than the Moon, for from here to 
the orb of day is 12,000 times the breadth of our planet. 
Here we must not think of erecting a triangle with the 
diameter of the Earth for its base: the two ideal lines 
drawn from the extremities of this diameter would 
come together between the Earth and the Sun; there 
would be no triangle, and the measurement would be 
absurd. 

In order to measure the distance which separates 
the Earth from the Sun, we have recourse to the fine 
planet Venus, whose orbit is situated inside the terres- 
trial orbit. Owing to the combination of the Earth's 
motion with that of the Star of the Morning and Evening, 
the capricious Venus passes in front of the Sun at the 
curious intervals of 8 years, 113I years less 8 years, 
8 years, 113J years plus 8 years. 

Thus there was a transit in June, 1 761, then another 
8 years after, in June, 1769. The next occurred 113 J 
years less 8 years, /. ^., 105I years after the preceding, 
in December, 1874; the next in December, 1882. The 
next will be in June, 2004, and June, 2012. At these 
eagerly anticipated epochs, astronomers watch the tran- 

296 



ON METHODS 

sit of Venus across the Sun at two terrestrial stations 
as far as possible removed from each other, marking 
the two points at which the planet, seen from their 
respective stations, appears to be projected at the same 
moment on the solar disk. This measure gives the 
width of an angle formed by two lines, which starting 
from two diametrically opposite points of the Earth, 
cross upon Venus, and form an identical angle upon the 
Sun. Venus is thus at the apex of two equal triangles, 
the bases of which rest, respectively, upon the Earth and 




B 

Fig. 83. — Measurement of the distance of the Sun. 

on the Sun. The measurement of this angle gives 
what is called the parallax of the Sun — that is, the angu- 
lar dimension at which the Earth would be seen at the 
distance of the Sun. 

Thus, it has been found that the half-diameter of 
the Earth viewed from the Sun measures W\%2, Now, 
we know that an object presenting an angle of one 
degree is at a distance of 57 times its length. 

The same object, if it subtends an angle of a minute, 
or the sixtieth part of a degree. Indicates by the measure- 

297 



ASTRONOMY FOR AMATEURS 

ment of its angle that it is 60 times more distant, /. e.^ 
3,438 times. 

Finally, an object that measures one second, or the 
sixtieth part of a minute, is at a distance of 206,265 
times its length. 

Hence we find that the Earth is at a distance from 
the Sun ^^—i^l-^ — that is, 23,386 times its half-diame- 
ter, that is, 149,000,000 kilometers (93,000,000 miles). 
This measurement again is as precise and certain as 
that of the Moon. 

I hope my readers will easily grasp this simple 
method of triangulation, the result of which indicates 
to us with absolute certainty the distance of the two 
great celestial torches to which we owe the radiant light 
of day and the gentle illumination of our nights. 

The distance of the Sun has, moreover, been con- 
firmed by other means, whose results agree perfectly 
with the preceding. The two principal are based on 
the velocity of light. The propagation of light is not 
instantaneous, and notwithstanding the extreme rapid- 
ity of its movements, a certain time is required for its 
transmission from one point to another. On the Earth, 
this velocity has been measured as 300,000 kilometers 
(186,000 miles) per second. To come from Jupiter to 
the Earth, it requires thirty to forty minutes, according 
to the distance of the planet. Now, in examining the 

298 



ON METHODS 

eclipses of Jupiter's satellites, it has been discovered that 
there is a difference of i6 minutes, 34 seconds in the 
moment of their occurrence, according as Jupiter is on 
one side or on the other of the Sun, relatively to the 
Earth, at the minimum and maximum distance. If the 
light takes 16 minutes, 34 seconds to traverse the terres- 
trial orbit, it must take less than that time, or 8 minutes, 
17 seconds, to come to us from the Sun, v^hich is situated 
at the center. Know^ing the velocity of light, the dis- 
tance of the Sun is easily found by multiplying 300,000 
by 8 minutes, 17 seconds, or 497 seconds, w^hich gives 
about 149,000,000 kilometers (93,000,000 miles). 

Another method founded upon the velocity of light 
again gives a confirmatory result. A familiar example 
will explain it: Let us imagine ourselves exposed to a 
vertical rain; the degree of inclination of our umbrella 
v^ill depend on the relation between our speed and that 
of the drops of rain. The more quickly we run, the 
more we need to dip our umbrella in order not to meet 
the drops of water. Now the same thing occurs for light. 
The stars, disseminated in space, shed floods of light 
upon the Heavens. If the Earth were motionless, the 
luminous rays would reach us directly. But our planet 
is spinning, racing, with the utmost speed, and in our 
astronomical observations we are forced to follow its 
movements, and to incline our telescopes in the direction 

2QQ 



ASTRONOMY FOR AMATEURS 

of its advance. This phenomenon, known under the 
name of aberration of Hght, is the result of the combined 
effects of the velocity of light and of the Earth's motion. 
It show^s that the speed of our globe is equivalent to 
YQ^Q-Q- that of light, /. ^., = about 30 kilometers (19 
miles) per second. Our planet accordingly accom- 
plishes her revolution round the Sun along an orbit 
w^hich she traverses at a speed of 30 kilometers (better 
29^) per second, or 1,770 kilometers per minute, or 
106,000 kilometers per hour, or 2,592,000 kilometers 
per day, or 946,080,000 kilometers (586,569,600 miles) 
in the year. This is the length of the elliptical path 
described by the Earth in her annual translation. 

The length of orbit being thus discovered, one can 
calculate its diameter, the half of which is exactly the 
distance of the Sun. 

We may cite one last method, whose data, based 
upon attraction, are provided by the motions of our sat- 
ellite. The Moon is a little disturbed in the regularity 
of her course round the Earth by the influence of the 
powerful Sun. As the attraction varies inversely with 
the square of the distance, the distance may be deter- 
mined by analyzing the eff'ect it has upon the Moon. 

Other means, on which we will not enlarge in this 
summary of the methods employed for determinations, 
confirm the precisions of these measurements with cer- 

300 



ON METHODS 

tainty. Our readers must forgive us for dwelling at 
some length upon the distance of the orb of day, since 
this measurement is of the highest importance; it serves 
as the base for the valuation of all stellar distances, and 
may be considered as the meter of the universe. 

This radiant Sun to which we owe so much is there- 
fore enthroned in space at a distance of 149,000,000 kilo- 
meters (93,000,000 miles) from here. Its vast brazier 
must indeed be powerful for its influence to be exerted 
upon us to such a manifest extent, it being the very 
condition of our existence, and reaching out as far as 
Neptune, thirty times more remote than ourselves from 
the solar focus. 

It is on account of its great distance that the Sun 
appears to us no larger than the Moon, which is only 
384,000 kilometers (238,000 miles) from here, and is 
itself illuminated by the brilliancy of this splendid orb. 

No terrestrial distance admits of our conceiving of 
this distance. Yet, if we associate the idea of space with 
the idea of time, as we have already done for the Moon, 
we may attempt to picture this abyss. The train cited 
just now would, if started at a speed of a kilometer a 
minute, arrive at the Sun after an uninterrupted course 
of 283 years, and taking as long to return to the Earth 
the total would be 566 years. Fourteen generations of 
stokers would be employed on this celestial excursion 

301 



ASTRONOMY FOR AMATEURS 

before the bold travelers could bring back news of the 
expedition to us. 

Sound is transmitted through the air at a velocity of 
340 meters (1,115 f^^^) P^r second. If our atmosphere 
reached to the Sun, the noise of an explosion sufficiently 
formidable to be heard here v^ould only reach us at the 
end of 13 years, 9 months. But the more rapid carriers, 
such as the telegraph, would leap across to the orb of 
day in 8 minutes, 17 seconds. 

Our imagination is confounded before this gulf of 
93,000,000 miles, across which we see our dazzling 
Sun, whose burning rays fly rapidly through space in 
order to reach us. 

And now let us see how the distances of the planets 
were determined. 

We will leave aside the method of which we have 
been speaking; that now to be employed is quite dif- 
ferent, but equally precise in its results. 

It is obvious that the revolution of a planet round the 
Sun will be longer in proportion as the distance is greater, 
and the orbit that has to be traveled vaster. This is 
simple. But the most curious thing is that there is a 
geometric proportion in the relations between the 
duration of the revolutions of the planets and their 
distances. This proportion was discovered by Kepler, 

302 



ON METHODS 

after thirty years of research, and embodied in the 
following formula: 

*^The squares of the times of revolution of the planets 
round the Sun (the periodic times) are proportional to 
the cubes of their mean distances from the Sun." 

This is enough to alarm the boldest reader. And 
yet, if we unravel this somewhat incomprehensible 
phrase, we are struck with its simplicity. 

What is a square? We all know this much; it is 
taught to children often years old. But lest it has slipped 
your memory: a square is simply a number multiplied 
by itself. 

Thus: 2 X 2 = 4; 4 is the square of 2. 

Four times 4 is 16; 16 is the square of 4. 

And so on, indefinitely. 

Now, what is a cube ? It is no more difficult. It is 
a number multiplied twice by itself. 

For instance: 2 multiplied by 2 and again by 2 equals 
8. So 8 is the cube of 2. 3 X 3 X 3 = 27; 27 is the 
cube of 3, and so on. 

Now let us take an example that will show the sim- 
plicity and precision of the formula enunciated above. 
Let us choose a planet, no matter which. Say, Jupiter, 
the giant of the worlds. He is the Lord of our planet- 
ary group. This colossal star is five times (precisely, 
5.2) as far from us as the Sun. 

303 



ASTRONOMY FOR AMATEURS 

Multiply this number twice by itself 5.2 X 5.2 
X 5.2 = 140. 

On the other hand, the revolution of Jupiter takes 
almost twelve years (11. 85^ This number multiplied 
by itself also equals 140. The square of the number 
11.85 is equal to the cube of the number 5-^- This very 
simple law regulates all the heavenly bodies. 

Thus, to find the distance of a planet, it is sufficient 
to observe the time of its revolution, then to discover 
the square of the given number by multiplying it into 
itself. The result of the operation gives simultaneously 
the cube of the number that represents the distance. 

To express this distance in kilometers (or miles), it is 
sufficient to multiply it by 149,000,000 (in miles 93,000,- 
ooo\, the key to the system of the world. 

Nothing, then, could be less complicated than the 
definition of these methods. A few moments of atten- 
tion reveal to us in their majestic simplicity the immut- 
able laws that preside over the immense harmony of the 
Heavens. 

But we must not confine ourselves to our own solar 
province. We have yet to speak of the stars that reign 
in infinite space far beyond our radiant Sun. 

Strange and audacious as it may appear, the human 
mind is able to cross these heights, to rise on the wings 



ox METHODS 

of eenius to these distant suns, and to plumb the depths 
of the ab\'ss that separates us from these celestial 
kingdoms. 

Here, we return to our first method, that of trianeu- 
lation. And the distance that separates us from the 
Sun must serve in calculating the distances of the stars. 

The Earth, spinning round the Sun at a distance of 
149,000,000 kilometers (93, 000. 000 miles , describes a 
circumference, or rather an ellipse, of 036,000.000 kilo- 
meters (580,320,000 miles\ which it travels over in a 
year. The distance of anv point of the terrestrial orbit 
from the diametricallv opposite point which it passes 
six months later is 298,000.000 kilometers '184,760,000 
miles , /. c-., the diameter of this orbit. This immense 
distance 'in comparison with those with which we are 
familiar' serves as the base of a triangle of which the 
apex is a star. 

The difficulty in exact measurements of the distance 
ot a star consists in observing the little luminous point 
persistently for a whole year, to see if this star is sta- 
tionary, or if it describes a minute ellipse reproducing; 
in perspective the annual revolution of the Earth. 

If it rem.ains fixed, it is lost in such depths of space 
that it is impossible to gage the distance, and our 
298,000,000 kilometers have no meanins: in view of 
such an ab}'ss. It. on the contrary*, it is displaced, it 

305 



ASTRONOMY FOR AMATEURS 



"S* 



will in the year describe a minute ellipse, which is only 
the reflection, the perspective in miniature, of the revo- 
lution of our planet round the Sun. 
The annual parallax of a star 
is the angle under which one 
would see the radius, or half-diam- 
eter, of the terrestrial orbit from 
it. This radius of 149,000,000 
kilometers (93,000,000 miles) is in- 
deed, as previously observed, the 
unit, the meter of celestial meas- 
ures. The angle is of course smaller 
in proportion as the star is more 
distant, and the apparent motion 
of the star diminishes in the same 
proportion. But the stars are all 
so distant that their annual dis- 
placement of perspective is almost 
imperceptible, and very exact in- 
struments are required for its de- 
tection. 

17 o c 11 The researches of the astrono- 

riG. 04, — omall ap- 
parent ellipses de- mers have proved that there is not 
scribed by the stars ^^^ g^^j^ f^j. which the parallax is 

as a result of the 1 1 r i ^t-i • 

, ,. - equal to that 01 another. 1 he mi- 

annual displace- ^ 

ment of the Earth. nuteness of this angle, and the ex- 
306 




''^fT 



ON METHODS 

traordinary difficulties experienced in measuring the 
distance of the stars, will be appreciated from the fact 
that the value of a second is so small that the displace- 
ment of any star corresponding with it could be covered 
by a spider's thread. 

A second of arc corresponds to the size of an ob- 
ject at a distance of 206,265 times its diameter; to a 
millimeter seen at 2c6 meters' distance; to a hair, j^ of a 
millimeter in thickness, at 20 meters' distance (more in- 
visible to the naked eye). And yet this value Is In excess 
of those actually obtained. In fact: — the apparent dis- 
placement of the nearest star is calculated at yVo" ^^ ^ 
second (o'^75), /• e., from this star, a of Centaur, the 
half-diameter of the terrestrial orbit is reduced to this 
infinitesimal dimension. Now in order that the length 
of any straight line seen from the front be reduced until 
it appear to subtend no more than an angle of o'^75, it 
must be removed to a distance 275,000 times Its length. 
As the radius of the terrestrial orbit is 149,000,000 kilo- 
meters (93,000,000 miles), the distance which separates 
a of Centaur from our world must therefore = 41,000,- 
000,000,000 kilometers (25,000,000,000,000 miles). And 
that is the nearest star. We saw in Chapter II that it 
shines in the southern hemisphere. The next, and one 
that can be seen in our latitudes, is 61 of Cygnus, which 
floats in the Heavens 68,000,000,000,000 kilometers 

21 307 



ASTRONOMY FOR AMATEURS 

(42,000,000,000,000 miles) from here. This Httle star, 
of fifth magnitude, was the first of which the distance 
was determined (by Bessel, 1837-1840). 

All the rest are much more remote, and the proces- 
sion is extended to infinity. 

We can not conceive directly of such distances, and 
in order to imagine them we must again measure space 
by time. 

In order to cover the distance that separates us from 
our neighbor, a of Centaur, light, the most rapid of all 
couriers, takes 4 years, 128 days. If we would follow it, 
we must not jump from start to finish, for that would 
not give us the faintest idea of the distance: we must take 
the trouble to think out the direct advance of the ray of 
light, and associate ourselves with its progress. We 
must see it traverse 300,000 kilometers (186^000 miles) 
during the first second of the journey; then 300,000 more 
in the second, whicli makes 600,000 kilometers; then once 
more 300,000 kilometers during the third, and so on 
without stopping for four years and four months. If we 
take this trouble we may realize the value of the figure; 
otherwise, as this number surpasses all that we are in 
the habit of realizing, it will have no significance for us, 
and will be a dead letter. 

If some appalling explosion occurred in this star, and 
the sound in its flight of 340 meters (1,115 ^^^0 P^^^ 

^08 



ON METHODS 

second were able to cross the void that separates us from 
it, the noise of this explosion would only reach us in 
3,000,000 years. 

A train started at a speed of io6 kilometers 
(65 miles) per hour would have to run for 46,000,000 
years, in order to reach this star, our neighbor in the 
celestial kingdom. 

The distance of some thirty of the stars has been 
determined, but the results are dubious. 

The dazzling Sirius reigns 92,000,000,000 kilo- 
meters (57,000,000,000 miles), the pale Vega at 204,=- 
000,000,000. Each of these magnificent stars must be a 
huge sun to burn at such a distance with such luminosity. 
Some are millions of times larger than the Earth. Most 
of them are more voluminous than our Sun. On all 
sides they scintillate at inaccessible distances, and their 
light strays a long while in space before it encounters 
the Earth. The luminous ray that we receive to-day 
from some pale star hardly perceptible to our eyes — 
so enormous is its distance — may perhaps bring us 
the last emanation of a sun that expired thousands of 
years ago. 

If these methods have been clear to my readers, 
they may also be interested perhaps in knowing the 
means employed in weighing the worlds. The process 



ASTRONOMY FOR AMATEURS 

IS as simple and as clear as those of which we have 
been speaking. 

Weighing the stars! Such a pretension seems 
Utopian, and one asks oneself curiously what sort 
of balance the astronomers must have adopted in 
order to calculate the weight of Sun, Moon, planets 
or stars. 

Here, figures replace weights. Ladies proverbially 
dislike figures: ytt. it would be easier for some society 
dame to weigh the Sun at the point of her pen, by writing 
down a few columns of figures with a little care, than 
to weigh a 12 kilogram case of fruit, or a dress-basket 
of 35 kilos, by direct methods. 

Weighing the Sun is an amusement like any other, 
and a change of occupation. 

If the Moon were not attracted by the Earth, she 
would glide through the Heavens along an indefinite 
straight line, escaping at the tangent. But in virtue of 
the attraction that governs the movements of all the 
Heavenly bodies, our satellite at a distance of 60 times 
the terrestrial half-diameter revolves round us in 
27 days, 7 hours, 43 minutes, iij seconds, continually 
leaving the straight line to approach the Earth, and 
describing an almost circular orbit in space. If at any 
moment we trace an arc of the lunar orbit, and if a 
tangent is taken to this arc, the deviation from the 

310 



ON METHODS 

straight line caused by the attraction of our planet is 
found to be i^ millimeter per second. 

This is the quantity by which the Moon drops 
toward us in each second, during which she accom- 
plishes 1,017 rneters of her orbit. 

On the other hand, no body can fall unless it be 
attracted, drawn by another body of a more powerful 
mass. 

Beings, animals, objects, adhere to the soil, and 
weigh upon the Earth, because they are constantly 
attracted to it by an irresistible force. 

Weight and universal attraction are one and the 
same force. 

On the other hand, it can be determined that if an 
object is left to itself upon the surface of the Earth, it 
drops 4.90 meters during the first second of its fall. 

We also know that attraction diminishes with the 
square of the distance, and that if we could raise a stone 
to the height of the Moon, and then abandon it to the 
attraction of our planet, it would in the first second fall 
4.90 meters divided by the square of 60, or 3,600 — that 
is, of i^ millimeters, exactly the quantity by which the 
Moon deviates from the straight line she would pursue 
if the Earth were not influencing her. 

The reasoning just stated for the Moon is equally 
applicable to the Sun. 



ASTRONOMY FOR AMATEURS 

The distance of the Sun is 23,386 times the radius 
of the Earth. In order to know how much the intensity 
of terrestrial weight would be diminished at such a dis- 
tance, we should look, in the first place, for the square 
of the number representing the distance — that is, 23,386 
multiplied by itself, = 546,905,000. If we divide 4.90 
meters, which represents the attractive force of our 
planet, by this number, we get y-o-ro Fo"o ^^ ^ millimeter, 
and we see that at the distance of the Sun, the Earth's 
attraction would really be almost ml. 

Now let us do for our planet what we did for its 
satellite. Let us trace the annual orbit of the terres- 
trial globe round the central orb, and we shall find that 
the Earth falls in each second 2.9 millimeters toward 
the Sun. 

This proportion gives the attractive force of the 
Sun in relation to that of the Earth, and proves that the 
Sun is 324,000 times more powerful than our world, 
for 2.9 millimeters divided by 0.000,009 equals 324,000, 
if worked out into the ultimate fractions neglected here 
for the sake of simplicity. 

A great number of stars have been weighed by the 
same method. 

Their mass is estimated by the movement of a 
satellite round them, and it is by this method that we 
are able to affirmx that Jupiter is 310 times heavier than 

312 



ON METHODS 

the Earth, Saturn 92 times, Neptune 16 times, Uranus 
14 times, while Mars is much less heavy, its weight being 
only two-thirds that of our own. 

The planets which have no satellites have been 
weighed by the perturbations which they cause in other 
stars, or in the imprudent comets that sometimes tarry 
in their vicinity. Mercury weighs very much less than 
the Earth (only y^-q) and Venus about -^-q. So the 
beautiful star of the evening and morning is not so 
light as her name might imply, and there is no great dif- 
ference between her weight and our own. 

As the Moon has no secondary bodv submitted to 
her influence, her weight has been calculated by reckon- 
ing the amount of water she attracts at each tide in 
the ocean, or by observing the effects of her attraction on 
the terrestrial globe. When the Moon is before us, in 
the last quarter, she makes us travel faster, whereas 
in the first quarter, when she is behind, she delays us. 

All the calculations agree in showing us that the orb 
of night is 81 times less heavy than our planet. There 
is nearly as much difference in weight between the Earth 
and the Moon as between an orange and a grape. 

Not content with weighing the planets of our system, 
astronomers have investigated the weight of the stars. 
How have they been enabled to ascertain the quantity 

3^3 



ASTRONOMY FOR AMATEURS 

of matter which constitutes these distant Suns — incan- 
descent globes of fire scattered in the depths of space ? 

They have resorted to the same method, and it is by 
the study of the attractive influence of a sun upon some 
other contiguous neighboring star, that the weight of a 
few of these has been calculated. 

Of course this method can only be applied to those 
double stars of which the distance is known. 

It has been discovered that some of the tiny stars 
that we can hardly see twinkling in the depths of the 
azure sky are enormous suns, larger and heavier than 
our own, and millions of times more voluminous than 
the Earth. 

Our planet is only a grain of dust floating in the 
immensity of Heaven. Yet this atom of infinity is the 
cradle of an immense creation incessantly renewed, and 
perpetually transformed by the accumulated centuries. 

And what diversity exists in this army of worlds and 
suns, whose regular harmonious march obeys a mute 
order. . . . 

But we have as yet said nothing about weight on the 
surface of the worlds, and I see signs of impatience in 
my readers, for after so much simple if unpoetical demon- 
stration, they will certainly ask me for the explanation 
that will prove to them that a kilogram transported to 
Jupiter or Mars would weigh more or less than here. 



ON METHODS 

Give me your attention five minutes longer, and I v^ill 
restore your faith in the astronomers. 

It must not be supposed that objects at the surface 
of a v^orld Hke Jupiter, 310 times heavier than our ow^n, 
weigh 310 times more. That v^ould be a serious error. 
In that case we should have to assume that a kilogram 
transported to the surface of the Sun would there weigh 
324,000 times more, or 324,000 kilograms. That would 
be correct if these orbs were of the same dimensions as 
the Earth. But to speak, for instance, only of the divine 
Sun, we know that he is 108 times larger than our little 
planet. 

Now, weight at the surface of a celestial body depends 
not only on its mass, but also on its diameter. 

In order to know the weight of any body upon the 
surface of the Sun, we must argue as follows: 

Since a body placed upon the surface of the Sun is 
108 times farther from its center than it is upon a globe 
of the dimensions of the Earth, and since, on the other 
hand, attraction diminishes with the square of the dis- 
tance, the intensity of the weight would there be 108 
multiplied by 108, or 11,700 times weaker. Now divide 
the number representing the mass, /. ^., 324,000, by this 
number 11,700, and it results that bodies at the surface 
of the Sun are 28 times heavier than here. A woman 
whose weight was 60 kilos would weigh 1,680 kilograms 

315 



ASTRONOMY FOR AMATEURS 

there if organized in the same way as on the Earth, and 
would find walking very difficult, for at each step she 
would lift up a shoe that weighed at least ten kilograms. 

This reasoning as just stated for the Sun may be ap- 
plied to the other stars. We know that on the surface 
of Jupiter the intensity of weight is twice and a third 
times as great as here, while on Mars it only equals y^Q. 

On the surface of Mercury, weight is nearly twice as 
small again as here. On Neptune it is approximately 
equal to our own. 

With deference to the Selenites, everything is at its 
lightest on the Moon: a man weighing 70 kilograms on 
the Earth would not weigh more than 12 kilos there. 

So all tastes can be provided for: the only thing to be 
regretted is that one can not choose one's planet with 
the same facility as one's residence upon the Earth. 



316 



CHAPTER XII 

LIFE, UNIVERSAL AND ETERNAL 

And now, while thanking my readers for having 
followed me so far in this descriptive account of the 
marvels of the Cosmos, I must inquire what philosoph- 
ical impression has been produced on their minds by- 
these celestial excursions to the other worlds ? Are 
you left indifferent to the pageant of the Heavens ? 
When your imagination was borne away to these distant 
stars, suns of the infinite, these innumerable stellar 
systems disseminated through a boundless eternity, did 
you ask what existed there, what purpose was served by 
those dazzling spheres, what effects resulted from these 
forces, radiations, energies ? Did you reflect that the 
elements which upon our little Earth determined a vital 
activity so prodigious and so varied must needs have 
spread the waves of an incomparably vaster and more 
diversified existence throughout the immensities of the 
Universe ? Have you felt that all can not be dead and 
deserted, as we are tempted by the illusions of our ter- 
restrial senses and of our isolation to believe in the 
silence of the night: that on the contrary, the real aim of 



ASTRONOMY FOR AMATEURS 

Astronomy, instead of ending with statements of the 
positions and movements of the stars, is to enable us to 
penetrate to them, to make us divine, and know^, and 
appreciate their physical constitution, their degree of 
life and intellectuality in the universal order ? 

On the Earth, it is Life and Thought that flourish; 
and it is Life and Thought that we seek again in these 
starry constellations strew^n to Infinitude amid the im- 
measurable fields of Heaven. 

The humble little planet that we inhabit presents 
itself to us as a brimming cup, overflowing at every 
outlet. Life is everywhere. From the bottom of the 
seas, from the valleys to the mountains, from the vege- 
tation that carpets the soil, from the mold in the fields 
and woods, from the air we breathe^ arises an immense, 
prodigious, and perpetual murmur. Listen! it is the 
great voice of Nature, the sum of all the unknown and 
mysterious voices that are forever caUing to us, from 
the ocean waves, from the forest winds, from the 300,000 
kinds of insects that are redundant everywhere, and 
make a lively community on the surface of our globe. A 
drop of water contains thousands of curious and agile 
creatures. A grain of dust from the streets of Paris is 
the home of 130,000 bacteria. If we turn over the soil of 
a garden, field, or meadow, we find the earthworms work- 
ing to produce assimilable slime. If we Hft a stone in the 

318 



LIFE, UNIVERSAL AND ETERNAL 

path, we discover a crawling population. If we gather 
a flower, detach a leaf, we everywhere find little insects 
living a parasitic existence. Swarms of midges fly in 
the sun, the trees of the wood are peopled wuth nests, 
the birds sing, and chase each other at play, the lizards 
dart away at our approach, we trample down the ant- 
heaps and the molehills. Life enwraps us in an inex- 
orable encroachment of w^hich we are at once the heroes 
and the victims, perpetuating itself to its own detriment, 
as imposed upon it by an eternal reproduction. And 
this from all time, for the very stones of which we build 
our houses are full of fossils so prodigiously multiplied 
that one gram of such stone will often contain millions 
of shells, marvels of geometrical perfection. The in- 
finitely little is equal to the infinitely great. 

Life appears to us as a fatal law, an imperious force 
which all obey, as the result and the aim of the associa- 
tion of atoms. This is illustrated for us upon the Earth, 
our only field of direct observation. We must needs be 
blind not to see this spectacle, deaf not to hear its 
reaching. On what pretext could one suppose that our 
little globe which, as we have seen, has received no 
privileges from Nature, is the exception; and that the 
entire Universe, save for one insignificant isle, is devoted 
to vacancy, solitude, and death ? 

We have a tendency to imagine that Life can not exist 



ASTRONOMY FOR AMATEURS 

under conditions other than terrestrial, and that the 
other worlds can only be inhabited on the condition 
of being similar to our own. But terrestrial nature itself 
demonstrates to us the error of this way of thinking. 
We die in the water: fishes die out of the water. Again, 
short-sighted naturalists affirm categorically that Life 
is impossible at the bottom of the sea: i, because it is 
in complete darkness; 2, because the terrible pressure 
would burst any organism; 3, because all motion would 
be impossible there, and so on. Some inquisitive person 
sends down a dredge, and brings up lovely creatures, so 
delicate in structure that the daintiest touch must proceed 
with circumspection. There is no light in these depths: 
they make it with their own phosphorescence. Other 
inquirers visit subterranean caverns, and discover ani- 
mals and plants whose organs have been transformed by 
adaptation to their gloomy environment. 

What right have we to say to the vital energy that 
radiates round every Sun of the Universe: ''Thus far 
shalt thou come, and no further"? In the name of 
Science ? An absolute mistake. The Known is an in- 
finitesimal island in the midst of the vast ocean of the 
Unknown. The deep seas which seemed to be a barrier 
are, as we have seen, peopled with special life. Some 
one objects: But after all, there is air there, there is oxy- 
gen: oxygen is indispensable: a world without oxygen 

320 



LIFE, UNIVERSAL AND ETERNAL 

would be a world of death, an eternally sterile desert. 
Why ? Because we have not yet come across beings 
that can breathe without air, and live without oxygen ? 
Another mistake. Even if we did not know of any, it 
would not prove that they do not exist. But as it hap- 
pens, we do know of such: the ancerobia. These beings 
live without air, without oxygen. Better still: oxygen 
kills them! 

All the evidence goes to show that in interpreting 
as we ought the spectacle of terrestrial life, and the posi- 
tive facts acquired by Science, we should enlarge the 
circle of our conceptions and our judgments, and not 
limit extra-terrestrial existence to the servile image of 
what is in existence here below. Terrestrial organic 
forms are due to local causes upon our planet. The 
chemical constitution of water and of the atmosphere, 
temperature, light, density, weight, are so many elements 
that have gone to form our bodies. Our flesh is com- 
posed of carbon, nitrogen, hydrogen, and oxygen com- 
bined in the state of water, and of some other elements, 
among which we may instance sodium chloride (salt). 
The flesh of animals is not chemically diff'erent from our 
own. All this comes from the water and the air, and 
returns to them again. The same elements, in very 
minute quantities, make up all living bodies. The ox 
that browses on the grass is formed of the same flesh 

321 



ASTRONOMY FOR AMATEURS 

as the man who eats the beef. All organized terrestrial 
matter is onlv carbon combined in variable proportions 
with hydrogen, nitrogen, oxygen, etc. 

But we have no right to forbid Xature to act differ- 
ently in worlds from which carbon is absent. A world, 
for example, in which silica replaces carbon, silicic acid 
carbonic acid, might be inhabited by organisms abscr^ 
lutely different from those which exist on the Earth, 
different not only in form, but also in substance. We 
already know stars and suns for which spectral analysis 
reveals a predominance of silica, t\ g., Rigel and Deneb. 
In a world where chlorine predominated, we might 
expect to find hydrochloric acid, and all the fecund 
family of chlorides, playing an important part in the 
phenomena of life. Might not bromine be associated 
in other formations : ^^ h\\ indeed, should we draw the 
line at terrestrial chemistry : What is to prove that 
these elements are really simple .' May not hydrogen, 
carbon, oxygen, nitrogen, and sulphur all be compounds ? 
Their equivalents are multiples of the first: i, 6, 8, 14, 
16. And is even hydrogen the most simple of the 
elements .' Is not its molecule composed of atoms, and 
may there not exist a single species of primitive atom, 
whose geometric arrangement and various associations 
might constitute the molecules of the so-called simple 
elements .' 

322 



LIFE, UNIVERSAL AND ETERNAL 

In our own solar system we discover the essential 
differences between certain planets. In the spectrum 
of Jupiter, for instance, we are aware of the action of an 
unknown substance that manifests itself by a marked 
absorption of certain red rays. This gas, which does not 
exist upon the Earth, is seen still more obviously in the 
atmospheres of Saturn and Uranus. Indeed, upon this 
last planet the atmosphere appears, apart from its water 
vapor, to have no sort of analogy with our ow^n. And 
in the solar spectrum itself, many of the lines have not 
yet been identified with terrestrial substances. 

The interrelation of the planets is of course incon- 
trovertible, since they are all children of the same parent. 
But they differ among themselves, not merely in respect 
of situation, position, volume, mass, density, temperature, 
atmosphere, but again in physical and chemical con- 
stitution. And the point we would now accent is that 
this diversity should not be regarded as an obstacle 
to the manifestations of life, but, on the contrary, as 
a new field open to the infinite fecundity of the uni- 
versal mother. 

When our thoughts take wing, not only to our neigh- 
bors. Moon, Venus, Mars, Jupiter, or Saturn, but still 
more toward the myriads of unknown worlds that 
gravitate round the suns disseminated in space, we have 
no plausible reason for imagining that the inhabitants 
22 323 



ASTRONOMY FOR AMATEURS 

of these other worlds of Heaven resemble us in any way, 
whether in form, or even in organic substance. 

The substance of the terrestrial human body is due 
to the elements of our planet, and notably to carbon. 
The terrestrial human form derives from the ancestral 
animal forms to which it has gradually raised itself by 
the continuous progress of the transformation of species. 
To us it seems obvious that we are man or woman, be- 
cause we have a head, a heart, lungs, two legs, two arms, 
and so on. Nothing is less a matter of course. That 
we are constituted as we are, is simply the result of our 
pro-simian ancestors having also had a head, a heart, 
lungs, legs, and arms — less elegant than your own, it is 
true. Madam, but still of the same anatomy. And 
more and more, by the progress of paleontology, we are 
delving down to the origin of beings. As certain as it is 
that the bird derives from the reptile by a process of or- 
ganic evolution, so certain is it that terrestrial Humanity 
represents the topmost branches of the huge genealogical 
tree, whereof all the limbs are brothers, and the roots of 
which are plunged into the very rudiments of the most 
elementary and primitive organisms. 

The multitude of worlds is surely peopled by every 
imaginable and unimaginable form. Terrestrial man 
is endowed with five senses, or perhaps it is better to say 
six. Why should Nature stop at this point ^ Why, for 

324 



LIFE, UNIVERSAL AND ETERNAL 

instance, may she not have given to certain beings an 
electrical sense, a magnetic sense, a sense of orientation, 
an organ able to perceive the ethereal vibrations of the 
infra-red or ultra-violet, or permitted them to hear at a 
distance, or to see through walls ? We eat and digest 
like coarse animals, v^e are slaves to our digestive tube: 
may there not be worlds in which a nutritive atmosphere 
enables its fortunate inhabitants to dispense with this 
absurd process ? The least sparrow, even the dusky 
bat, has an advantage over us in that it can fly through 
the air. Think how inferior are our conditions, since 
the man of greatest genius, the most exquisite woman, 
are nailed to the soil like any vulgar caterpillar before 
its metamorphosis! Would it be a disadvantage to in- 
habit a world in which we might fly w^hither we would; 
a world of scented luxury, full of animated flowers; a 
world where the winds would be incapable of exciting 
a tempest, where several suns of different colors — the 
diamond glowing with the ruby, or the emerald with the 
sapphire — would burn night and day (azure nights and 
scarlet days) in the glory of an eternal spring; with 
multi-colored moons sleeping in the mirror of the wa- 
ters, phosphorescent mountains, aerial inhabitants, — 
men, women, or perhaps of other sexes, — perfect in 
their forms, gifted with multiple sensibilities, luminous 
at will, incombustible as asbestos, perhaps immortal, 

325 



ASTRONOMY FOR AMATEURS 

unless they commit suicide out of curiosity ? Lilliputian 
atoms as we are, let us once for all be convinced that 
our imagination is but sterility, in the midst of an in- 
finitude hardly glimpsed by the telescope. 

One important point seems always to be ignored 
expressly by those who blindly deny the doctrine of the 
plurality of worlds. It is that this doctrine does not 
apply more particularly to the present epoch than to 
any other. Our time is of no importance, no absolute 
value. Eternity is the field of the Eternal Sow^er. There 
is no reason why the other worlds should be inhabited 
now more than at any other epoch. 

What, indeed, is the Present Moment ? It is an open 
trap through which the Future falls incessantly into the 
gulf of the Past. 

The immensity of Heaven bears in its bosom cradles 
as well as tombs, worlds to come and perished worlds. 
It abounds in extinct suns, and cemeteries. In all 
probability Jupiter is not yet inhabited. What does this 
prove ? The Earth was not inhabited during its primor- 
dial period: what did that prove to the inhabitants of 
Mars or of the Moon, who were perhaps observing it at 
that epoch, a few million years ago t 

To pretend that our globe must be the only inhab- 
ited world because the others do not resemble it, is to 
reason, not like a philosopher, but, as we remarked 

326 



LIFE, UNIVERSAL AND ETERNAL 

before, like a fish. Every rational fish ought to assume 
that it is impossible to live out of v^ater, since its outlook 
and its philosophy do not extend beyond its daily life. 
There is no answer to this order of reasoning, except 
to advise a little w^ider perception, and extension of the 
too narrow^ horizon of habitual ideas. 

For us the resources of Nature may be considered 
infinite, and ^'positive" science, founded upon our senses 
only, is altogether inadequate, although it is the only 
possible basis of our reasoning. We must learn to see 
w^ith the eyes of our spirit. 

As to the planetary systems other than our own, we 
are no longer reduced to hypotheses. We already know 
with certainty that our Sun is no exception, as was sug- 
gested, and is still maintained, by some theorists. The 
discovery in itself is curious enough. 

It is surely an exceptional situation that, given a si- 
dereal system composed of a central sun, and of one or 
more stars gravitating round him, the plane of such a 
system should fall just within our line of vision, and 
that it should revolve in such a way that the globes of 
which it is composed pass exactly between this sun and 
ourselves in turning round him, eclipsing him more or 
less during this transit. As, on the other hand, the 
eclipses would be our only means of determining the 
existence of these unknown planets (save indeed from 

327 



ASTRONOMY FOR AMATEURS 

perturbation, as in the case of Sirius and Procyon), it 
might have seemed quixotic to hope for Hke conditions 
in order to discover solar systems other than our own. 
But these exceptional circumstances have reproduced 
themselves at different parts of the Heavens. 

Thus, for instance, we have seen that the variable 
star Algol owes its variations in brilliancy, which reduce 
it from second to fourth magnitude every sixty-nine 
hours, to the interposition of a body between itself and 
the Earth, and celestial mechanics has already been 
able to determine accurately the orbit of this body, its 
dimensions and its mass, and even the flattening of the 
sun Algol. Here, then, is a system in which we know 
the sun and an enormous planet, whose revolution is 
effected in sixty-nine hours with extreme rapidity, as 
measured by the spectroscope. 

The star d of Cepheus is in the same case: it is an orb 
eclipsed in a period of 129 hours, and its eclipsing planet 
also revolves in the plane of our vision. The variable 
star in Ophiuchus has an analogous system, and obser- 
vation has already revealed a great number of others. 

Since, then, a certain number of solar systems dif- 
fering from our own have been revealed, as it were in 
section, to terrestrial observation, this affords us suf- 
ficient evidence of the existence of an innumerable 
quantity of solar systems scattered through the im- 

328 



LIFE, UNIVERSAL AND ETERNAL 

mensities of space, and we are no longer reduced to 
conjecture. 

On the other hand, analysis of the motions of several 
stars, such as Sirius, Procyon, Altair, proves that these 
distant orbs have companions, — planets not yet dis- 
covered by the telescope, and that perhaps never v^ill 
be discovered, because they are obscure, and lost in the 
radiation of the star. 

Some savants have asserted that Life can not ger- 
minate if the conditions of the environment differ too 
much from terrestrial conditions. 

This hypothesis is purely gratuitous, and v^e will 
now discuss it. 

In order to examine what is happening on the Earth, 
let us mount the ladder of time for a moment, to follow 
the evolutions of Nature. 

There was an epoch when the Earth did not exist. 
Our planet, the future world of our habitation, slept 
in the bosom of the solar nebula. 

At last it came to birth, this cherished Earth, a gase- 
ous, luminous ball, poor reflection of the King of Orbs, 
its parent. Millions of years rolled by before the con- 
densation and cooling of this new globe were sufl&ciently 
transformed to permit life to manifest itself in its most 
rudimentary aspects. 



ASTRONOMY FOR AMATEURS 

The first organic forms of the protoplasm, the first 
aggregations of cells, the protozoons, the zoophytes or 
plant-animals, the gelatinous mussels of the still warm 
seas, were succeeded by the fishes, then by the reptiles, 
the birds, the mammals, and lastly man, who at present 
occupies the top of the genealogical tree, and crowns 
the animal kingdom. 

Humanity is comparatively young upon the Earth. 
We may attribute some thousands of centuries of exist- 
ence to It . . . — and some five years of reason! 

The terrestrial organisms, from the lowest up to man, 
are the resultant of the forces in action at the surface of 
our planet. The earliest seem to have been produced 
bv the combinations of carbon with hvdrogen and ni- 
trogen; they were, so to speak, without animation, save 
for some very rudimentary sensibility; the sponges, 
corals, polyps, and medusae, give us a notion of these 
primitive beings. They were formed in the tepid waters 
of the primary epoch. As long as there were no con- 
tinents, no islands emerging from the level of the uni- 
versal ocean, there were no beings breathing in the air. 
The first aquatic creatures were succeeded by the 
amphibia, the reptiles. Later on were developed the 
mammals and the birds. 

What, again, do we not owe to the plant-world of the 
primary epoch, of the secondarv epoch, of the tertiary 

330 



LIFE, UNIVERSAL AND ETERNAL 

epoch, which slowlv prepared the good nutritious soil 
of to-dav, in which the roses flourish, and the peach and 
strawberry ripen ? 

Before it gave birth to a Helen or a Cleopatra, life 
manifested itself under the roughest forms, and in the 
most varied conditions. A long-period comet passing 
in sight of the Earth from time to time would have seen 
modifications of existence in each of its transits, in 
accordance with a slow evolution, corresponding to the 
variation of the conditions of existence, and progressing 
incessantly, for if Life is the goal of nature, Progress is 
the supreme law. 

The history of our planet is the history of life, with 
all its metamorphoses. It is the same for all the 
worlds, with some exceptions of orbs arrested in their 
development. 

The constitution of living beings is in absolute rela- 
tion with the substances of which thev are composed, the 
environment in which they move, temperature, light, 
weight, density, the leno-th of day and ni2:ht, the sea- 
sons, etc. — in a word, with all the cosmographic ele- 
ments of a world. 

If, for example, we compare between themselves two 
w^orlds such as the Earth and Neptune, utterly different 
from the point of view of distance from the Sun, we could 
not for an instant suppose that organic structures could 



ASTRONOMY FOR AMATEURS 

have followed a parallel development on these planets. 
The average temperature must be much lov^er on Nep- 
tune than on the Earth, and the same holds for intensity 
of light. The years and seasons there are 165 times 
longer than with us, the density of matter is three times 
as weak, and weight is, on the contrary, a little greater. 
Under conditions so different from our own, the activi- 
ties of Nature would have to translate themselves un- 
der other forms. And doubtless the elementary bodies 
would not be found there in the same proportions. Con- 
sequently we have to conclude that organs and senses 
would not be the same there as here. The optic nerve, 
for instance, which has formed and developed here from 
the rudimentary organ of the trilobite to the marvels of 
the human eye, must be incomparably more sensitive 
upon Neptune than in our dazzling solar luminosity, 
in order to perceive radiations that we do not perceive 
here. In all probability, it is replaced there by some 
other organ. The lungs, functioning there in another 
atmosphere, are different from our own. So^ too, for 
the stomach and digestive organs. Corporeal forms, 
animal and human, can not resemble those which exist 
upon the Earth. 

Certain savants contend that if the conditions dif- 
fered too much from terrestrial conditions, life could 
not be produced there at all. Yet we have no right to 

332 



LIFE, UNIVERSAL AND ETERNAL 

limit the powers of Nature to the narrow bounds of our 
sphere of observation, and to pretend that our planet 
and our Humanity are the type of all the worlds. 
That is a hypothesis as ridiculous as it is childish. 

Do not let us be "personal/* like children, and old 
people who never see beyond their room. Let us learn 
to live in the Infinite and the Eternal 

From this larger point of view, the doctrine of the 
plurality of worlds is the complement and the natural 
crown of Astronomy. What interests us most in the 
study of the Universe is surely to know what goes on 
there. 

These considerations show that, in all the ages, what 
really constitutes a planet is not its skeleton but the life 
that vibrates upon its surface. 

And again, if we analyze things, we see that for the 
Procession of Nature, life is all, and matter nothing. 

What has become of our ancestors, the millions of 
human beings who preceded us upon this globe : Where 
are their bodies r What is left of them r Search every- 
where. Nothing is left but the molecules of air, water, 
dust, atoms of hydrogen, nitrogen, oxygen, carbon, etc., 
which are incorporated in turn in the organism of every 
living being. 

The whole Earth is a vast cemetery, and its finest 

333 



ASTRONOMY FOR AMATEURS 

cities are rooted in the catacombs. But now, in crossing 
Paris, I passed for at least the thousandth time near the 
Church of St. Germain-FAuxerrois, and was obhged 
to turn out of the direct way, on account of excavations. 
I looked down, and saw that immediately below the 
pavement, they had just uncovered some stone coffins 
still containing the skeletons that had reposed there for 
ten centuries. From time immemorial the passers-by had 
trampled them unwittingly under foot. And I reflected 
that it is much the same in every quarter of Paris. Only 
yesterday, some Roman tombs and a coin with the effigy 
of Nero were found in a garden near the Observatory. 

And from the most general standpoint of Life, the 
whole world is in the same case, and even more so, seeing 
that all that exists, all that lives, is formed of elements 
that have already been incorporated in other beings, no 
longer living. The roses that adorn the bosom of the 
fair . . . but I will not enlarge upon this topic. 

And you, so strong and virile, of what elements is 
your splendid body formed ? Where have the elements 
you absorb to-day in respiration and assimilation been 
drawn from, what lugubrious adventures have they 
been subject to ? Think av/ay from it: do not insist on 
this point: on no account consider it. . . . 

And yet, let us dwell on it, since this reality is the 
most evident demonstration of the ideal; since what 

334 



LIFE, UNIVERSAL AND ETERNAL 

exists is you, Is all of us, is Lije\ and matter is only its 
substance, like the materials of a house, and even less so, 
since its particles only pass rapidly through the frame- 
work of our bodies. A heap of stones does not make 
a house. Quintillions of tons of materials would not 
represent the Earth or any other world. 

Yes, what really exists, what constitutes a complete 
orb, is the city of Life. Let us recognize that the flower 
of life flourishes on the surface of our planet, embellishing 
it with its perfume; that it is just this life that we see and 
admire, — of which we form part, — and which is the rai^ 
son d'etre of things; that matter floats, and crosses, and 
crosses back again, in the web of living beings, — and 
the reality, the goal, is not matter — it is the life matter 
is employed upon. 

Yes, matter passes, and being also, after sharing in 
the concerted symphony of life. 

And indeed everything passes rapidly! 

What irrepressible grief, what deep melancholy, 
what ineff'aceable regrets we feel, when as age comes on 
we look back, when we see our friends fallen upon the 
road one after the other, above all when we visit the 
beloved scenes of our childhood, those homes of other 
years, that witnessed our first start in terrestrial exist- 
ence, our first games, our first aff'ections — those affections 
of childhood that seemed eternal — when we wander over 

335 



ASTRONOMY FOR AMATEURS 

those fields and valleys and hills, when we see again the 
landscape whose aspect has hardly changed, and whose 
image is so intimately linked with our first impres- 
sions. There near this fireside the grandfather danced 
us on his knee, and told us blood-curdling stories; here 
the kind grandmother came to see if we were comfortably 
tucked in, and not likely to fall out of the big bed; in this 
little wood, along these alleys that seemed endless, we 
spread our nets for birds; in this stream we fished for 
crayfish; there on the path we played at soldiers with 
our elders, who were always captains; on these slopes we 
found rare stones and fossils, and mysterious petrifac- 
tions; on this hill we admired the fine sunsets, the ap- 
pearance of the stars, the form of the constellations. 
There we began to live, to think, to love, to form 
attachments, to dream, to question every problem, to 
breathe intellectually and physically. And now, where 
is this beloved grandfather ? the good grandmother ? 
where are all whom we knew in infancy ? where are our 
dreams of childhood ? Winged thoughts still seem to 
flutter in the air, and that is all. People, caresses, 
voices, all have gone and vanished. The cemetery has 
closed over them all. There is a silent void. Were all 
those fine and sunny hours an illusion ? Was it only 
to weep one day over this negation that our childish 
hearts were so tenderly attached to these fleeting 

336 



LIFE, UNIVERSAL AND ETERNAL 

shadows r Is there nothing, down the long length of 
human history, but eternal delusion ? 

It is here, above all, that we find ourselves in pres- 
ence of the greatest problems. Life is the goal, it is 
Life that produces the conditions of Thought. With- 
out Thought, where would be the Universe .? 

We feel that without life and thought, the Universe 
would be an empty theater, and Astronomy itself, sub- 
lime science, a vain research. We feel that this is the 
truth, veiled as yet to actual science, and that human 
races kindred with our own exist there in the immensi- 
ties of space. Yes, we feel that this is truth. 

But we would fain go a little further in our knowl- 
edge of the universe, and penetrate in some measure 
the secret of our destinies. We would know if these 
distant and unknown Humanities are not attached to us 
by mysterious cords, if our life, which will assuredly be 
extinguished at some definite moment here below, will 
not be prolonged into the regions of Eternity. 

A moment ago we said that nothing is left of the 
body. Millions of organisms have lived, there are no 
remains of them. Air, water, smoke, dust. Memento^ 
homOy quia pulvts es et in pulverem revertehis. Remember 
oh man! that dust thou art, and unto dust thou shalt 
return, says the priest to the faithful, when he scatters 
the ashes on the day after the carnival. 

337 



ASTRONOMY FOR AMATEURS 

The body disappears entirely. It goes where the 
corpse of Caesar went an hour after the extinction of his 
pyre. Nor will there be more remains of any of us. 
And the whole of Humanity, and the Earth itself, will 
also disappear one day. Let no one talk of the Progress of 
Humanity as an end! That would be too gross a decoy. 

If the soul were also to disappear in smoke, what 
would be left of the vital and intellectual organization 
of the world ? Nothing. 

On this hypothesis, all would be reduced to nothing. 

Our reason is not immense, our terrestrial faculties 
are sufficiently limited, but this reason and these faculties 
suffice none the less to make us feel the improbability, 
the absurdity, of this hypothesis, and we reject it as in- 
compatible with the sublime grandeur of the spectacle 
of the universe. 

Undoubtedly, Creation does not seem to concern 
itself with us. It proceeds on its inexorable course 
without consulting our sensations. With the poet we 
regret the implacable serenity of Nature, opposing the 
irony of its smiling splendor to our mourning, our revolts, 
and our despair. 

Que peu de temps suffit pour changer toutes choses! 

Nature au front serein, comme vous oubliez! 
Et comme vous brisez dans vos metamorphoses 

Les fils mysterieux ou nos coeurs sont lies. 

338 



LIFE, UNIVERSAL AND ETERNAL 

D'autres vont maintenant passer ou nous passames ; 

Nous y sommes venus, d'autres vont y venir, 
Et le songe qu'avaient ebauche nos deux ames, 

lis le continueront sans pouvoir le iinir. 

Car personne ici-bas ne termine et n'acheve; 

Les pires des humains sont comme les meilleurs ; 
Nous nous eveillons tous au meme endroit du reve : 

Tout commence en ce monde et tout finit ailleurs. 

Repondez, vallon pur, repondez, solitude! 

O Nature, abritee en ce desert si beau, 
Quand nous serons couches tous deux, dans T attitude 

Que donne aux morts pensifs la forme du tombeau, 

Est-ce que vous serez a ce point insensible, 

De nous savoir perdus, morts avec nos amours, 

Et de continuer votre fete paisible 

Et de toujours sourire et de chanter toujours?* 

Note. — Free Translation, 

How brief a time suffices for all things to change ! Serene- 
fronted Nature, too soon you will forget ! ... in your 
metamorphoses ruthlessly snapping the cords that bind our hearts 
together ! 

Others will pass where we pass ; we have arrived, and others 
will arrive after us : the thought sketched out by our souls will 
be pursued by theirs . . . — and they will not find the solution 
of it. 

For no one here begins or finishes : the worst are as the best 
of humans ; we all awake at the same moment of the dream : we 
all begin in this world, and end otherwhere. 

* Victor Hugo. Tristesse d' Olympia. 

23 339 



ASTRONOMY FOR AMATEURS 

Reply, sweet valley, reply, solitude ; O Nature, sheltering 
in this splendid desert, when we are both asleep, and cast by the 
tomb into the attitude of pensive death. 

Will you to the last verge be so insensible, that, knowing us 
lost, and dead with our loves, you will pursue your cheerful 
feast, and smile, and sing always? 

Yes, mortals may say that when they are sleeping in 
the grave, spring and summer will still smile and sing; 
husband and wife may ask themselves if they will meet 
again some day, in another sphere; but do we not feel 
that our destinies can not be terminated here, and that 
short of absolute and final nonentity for everything, 
they must be renewed beyond, in that starry Heaven to 
which every dream has flown instinctively since the first 
origins of Humanity ? 

As our planet is only a province of the Infinite 
Heavens, so our actual existence is only a stage in Eternal 
Life. Astronomy, by giving us wings, conducts us to 
the sanctuary of truth. The specter of death has de- 
parted from our Heaven. The beams of every star shed 
a ray of hope into our hearts. On each sphere Nature 
chants the paean of Life Eternal. 

THE END 



340 



INDEX 



Aberration, 300 

Adams, 168 

Agnesi, Marie, 5 

Alcar, 34 

Aldebaran, 44, 66 

Alexandria, 3 

Algol, 39 

Ancients, views of, 30 

Andrew Ellicot, 195 

Andromeda, 37, 38 

Angles, 289 

Antares, 45, 66, 70 

Antipodes, 208 

Arago, 275 

Arcturus, 39, 66 

Asteroids, 146, 195 

Astronomie des Dames, 9 

Attraction, 208 

Aureole, 279 

Autumn Constellations, 54 

Axis, 225 

B 

Babylonian Tables, 30 
Bartholomew Diaz, 176 
Bear, Little, 35 

Great, 32, 34, 35 
Betelgeuse, 49, 66 
Biela's Comet, 189, 198 



Bode's law, 167 
Bolides, 201 



Cancer, 72 
Capella, 38, 66 
Cassiopeia, 36 
Castor, 44, 68 
Catalogue of Lalande, 65 
Catharine of Alexandria, 3 
Centaur, 52, 64, 65, 80 
Ceres, 147 

Chaldean pastors, 30 
Chaldeans, 271 
Chariot of David, 32 
Charioteer, 38 
Chart of Mars, 140 
Chatelet, Marquise du, 4 
Chiron, The Centaur, 30, 51 
Chromosphere, 102 
Clairaut, 3 
Clerke, Agnes, 7 
Cnidus, 31 
Coggia's Comet, 187 
Comet of Biela, 197 

of i8ti, 186 

of 1858, 174 
Comets, III, 185 
Constellations, 28 

figures, of, 31 

Autumn, 54 



341 



ASTRONOMY FOR AMATEURS 



Constellations, Spring, 52 

Summer, 53 

Winter, 51 
Copernicus, 125 
Corona Borealis, 40 
Corona of the Sun, 104 
Cygnus, 40 

D 

de Blocqueville, Madame, 5 
de Breteuil, Gabrielle - Emi- 

lie, 4 
de Charriere, Madame, 5 
Deneb, 41 
des Brosses, 5 
Diaz, Bartholomew, 176 
Dipper, 32, 34 
Donati, 187 
Double star, stellar dial of, 

86 
Double stars, 68, 70 
Dragon, 36 
du Chatelet, Marquise, 4 

E 

Eagle, 41 
Earth, 205 

ancient notions of, 19 

distance from the sun, 215 

how sustained, 21 

inclination, 224 

in space, 20 

motion of, round the Sun, 
222 

movement of, 217 

rotundity of, 206 

viewed from Mars, 144 



Earth, viewed from Mercury, 
119 

viewed from Venus, 130 

weight , 210 
Eclipse of Sun, May, 1900, 

273 
Eclipses, 259 
Ellicot, Andrew, 195 
Entretiens sur la Pluralite 

des mondes, 9 
Equator, 225 
Eudoxus, 31 
Evening Star, 123 



Facul^, 98, 100 
Fire-balls, 198 
Flammarion's Lunar Ring, 

253 
Fleming, Mrs., 7 
Fontenelle, 9 
Foucault, 219 



Galileo, 95, 98, 125, 244 
Galle, 168 

Globe, divisions of, 226 
Great Bear, 32, 34, 35 
Great Dog, 50 
Grecian Calendar, 229 
Greek alphabet, 33 

H 



Hall, Mr., 143 
Halley, 181 



342 



INDEX 



Halley's Comet, 3, 175 
Heavens, map of, 61 
Hercules, 41, 66, 79 
Herdsman, 39 
Herschel, Caroline, 6 
He veil us, 246 
Hipparchus, 31 
Houses of the Sun, 43 
Huggins, Lady, 8 
Huyghens, 49 
Hyades, 44 
Hypatia, 3 



Janssen, 102 
Jupiter, 148 

satellites, 155 

telescopic aspect of, 150 



K 

Klumpke, Miss, 7 
Kovalevsky, Sophie, 6 



Lacaille, 292 

Lalande, 3, 9, 65, 292 

Latitudes, 226 

Leonids, 195 

Lepaute, Madame Hortense, 

3. 4 
Le Verrier, 167 
Little Bear, 35 
Little Dog, 50 
Lockyer, 102 



Longitudes, 226 

Lucifer, 122 

Lunar Apennines, 251 

landscape, 254 

topography, 252 
Lyre, 40 

M 

Mars, 131 

chart of, 140 
Measurement, 289 
Medes and Lydians, 266 
Mercury, 114 
Meteorites, 201 
Meteors, 190, 191 
Metonic Cycle, 271 
Milky Way, 78, 87 
Mira Ceti, 77 
Mitchell, Maria, 7 
Mizar, 34, 69 
Moon, 232 

diameter of, 242 

distance of, 292 

geological features of, 245 

map of, 247 

mountains of, 246 

phases of, 241 

photograph of, 240 

revolution of, 234 

rotation of, 242 

size of, 242 

temperature of, 250 

total eclipse of, 263 



N 

Nebula, in Andromeda, 
in Orion, 81 



343 



ASTRONOMY FOR AMATEURS 



82 



Nebula, in the Greyhounds, 

82 
Neptune, 65, 166 

revolution of, 169 
Newton, 181 
Nucleus, 95, 185 

O 

Orion, 48, 49, 81 



Parallax, 292, 293 

annual, 306 
Pearl, 40 
Pegasus, 38 
Penumbra. 96 
Periodic Comet, orbit of, i 
Perseids, 195 
Perseus, 38, 70, 78 
Phenician navigators, 30 
Phoebus, 67 
Photosphere, 10 1 
Piazzi, 147 
Planets, 109, 113, 146 

distances, no, 302 

orbits of, 115 

orbits of, 116 
Pleiades, 38, 39, 44, 83 

occult ation of, 85 
Pleione, 84 
Polaris, 63 
Pole-star, 34, 63 
Poles, 225 
Pollux, 44 
Pope Calixtus, 176 
Prodigies in the heavens, i 
Ptolemy, 31, 217 



R 

Radiant, 195 
Riccioli, 246 
Rigel, 49, 70 

Roberts, Mrs. Isaac, 



Saidak, 34 
Saros, 271 
Satellites, no 
Saturn, 156 

revolution of, 157 

satellites, 162, 165 

volume, 158 
Saturn's rings, 161 
Scarpellini, Madame, 7 
Scheiner, 95 
Schiaparelli, 139 
Secchi, Father, 7 
Seven Oxen, 32 
Sextuple star, 74 
Shepherd's Star, 11 
Shooting stars, 193, 194; 
Sirius, 66, 309 
Solar storms, 100 

flames, 105 

system, 65 
Somerville, Mrs., 6 
Spring constellations, 52 
Stars, distances. 62 

double, 68, 70 

first magnitude, 57 

number of , 60 

quadruple, 73 

second magnitude, 58 

shooting, 193, 194 

temporary, 77 



196 



344 



INDEX 



Stars, triple, 72 

variable, 75 

weight of, 313 
Star cluster in Hercules, 79 

in the Centaur, 80 
St. Catherine, 3 
Summer constellations, 53 
Sun, 88 

houses of the, 43 

measurement of distance, 
297 

photograph of, 96 

rotation, 99 

temperature of, 105 

total eclipse of, 276 

weight, 106 
Sun and Earth, comparative 

sizes of, 93 
Sun-spots, 95, 10 1 

telescopic aspect of, 97 



Temporary stars, 77, 78 

Three Kings, 49 

Total eclipse of the moon, 263 

of sun, 276 
Triangulation, 288 
Triple Star, 72 



U 

Umbra, 95 
Universe, 22, 23, 90 
Urania, 8, 9 
Uranoliths, 201, 204 
Uranus, 162 



V 

Variable stars, 75 
Vega, 40 
Venus, 121, 296 
phases of, 124 
Vesper, 122 
Victor Hugo, 24 



W 

Weighing worlds, 309 
Winter constellations, 51 



Zodiac, constellations of, 46, 

47 
Zones, 225 



(1) 



345 



B M 




003 6389333 



